יומן של Sandmats of the World

I recently went through the glabrous species of Argentina and Chile and thought I'd document my findings here (partially so I can remember what I learned). The primary species were E. klotzchii and E. serpens, but I also investigated E. catamarcensis and E. serpillifolia. In addition, I've included some notes on the mysterious pistillate perianth that is common in E. klotzchii and E. serpens. The work is based on the monograph by Subils 1977 (Las Especies de Euphorbia de la República Argentina). Lastly, this is meant to exclude plants similar to E. hypericifolia (e.g., E. hypericifolia, E. hyssopifolia, and E. nutans). That group is far too complicated for a simple weekend survey to resolve.

The difference between E. klotzchii, E. serpens, and other entire and rounded leafed species of the region
Ultimately, the difference is in the stipules. In E. serpens, the stipules are fused into a triangular scale-like structure. In E. klotzchii, the stipules are distinct in one way or another. Additionally, E. klotzchii commonly produces leaf maculations while this never seems to happen in E. serpens. Lastly, E. klotzchii often assumes a more succulent and condensed appearance (easily noticed if you go through these observations).

There are two other similar species to be aware of: E. micromera (syn. E. ruizlealii). Euphorbia micromera is distinguished by it's small, rounded glands, total lack of glandular appendages, hairy stipules, and hairy lobes of the cyathium (there are plenty observations to reference on iNaturalist from North America, though the leaves are slightly differently shaped in South America as can be seen here). Euphorbia amandi has more rounded leaves like the other species mentioned here but produces serrated leaves.

Euphorbia klotzchii
Subils uses E. ovalifolia as used by Boissier. Without going into the taxonomic details (as the citations vary between this author's use and Euphorbia PBI), E. ovalifolia is considered a synonym of E. klotzchii. Under E. ovalifolia, Subils uses three varieties: E. ovalifolia var. ovalifolia, E. ovalifolia var. argentina, and E. ovalifolia var. schizosepala. None of these names are currently accepted and may just represent forms of the species. However, they all indicate some interesting aspects of the species' morphological variability. I've included a photo of each below in an attempt to show the differences (you may have to visit the pages and zoom in to tell the differences). Let's start with var. schizosepala. Note the little fringed appendage at the base of the fruit. This is considered a perianth (a perianth is a collective term for sepals and petals). In var. schizosepala, the perianth is long and easily differentiated from the fruit. In var. argentina, it becomes smaller and less noticable. In var. ovalifolia, it is completely absent.

E. ovalifolia var. schizosepala (source observation).

E. ovalifolia var. argentina (source observation).

E. ovalifolia var. ovalifolia (source observation).

Euphorbia serpens
Similar to E. klotchii, E. serpens produces a perianth in Chile and Argentina. Subils considers the plants that produce a perianth to be var. microphylla and the ones that don't to be E. serpens. Again, these varieties are not currently accepted, but useful for illustrating differences.

E. serpens var. microphylla (source observation).

E. serpens var. microphylla or somewhat intermediate (source observation).

E. serpens var. serpens (source observation).

Intriguingly, E. serpens has produced a large perianth in only one other location worldwide. That other location is in the Alps, Europe. There, the stipules aren't even fused and the variety goes by E. serpens var. fissistipula.

E. serpens var. fissistipula (source observation).

Euphorbia catamarcensis and E. serpillifolia, the narrow-leafed species

Seeds are most easily used to distinguishing E. catamarcensis and E. serpillifolia, though Subils also mentions that E. catamarcensis has a small and round pistillate perianth while E. serpillifolia doesn't. Additionally, Subils uses truncate leaf apices for E. serpillifolia, though I'm doubtful of the utility of this characteristic as the leaves of the plants I've seen aren't obviously truncate. One thing I did notice, though, is that the leaves of the plants that seem to align with E. serpillifolia have much more strongly asymmetric leaves and appear to have more cylindrical fruits (the later, an observation supported by Subils' description).

That said, any identification of E. serpillifolia should be treated as tentative. The species forms a morphologically variable complex in North America that is likely polyphyletic. Also, the lack of serrations on many leaves in the observations I'm calling E. serpillifolia in South America is troubling. It would not surprise me at all if the South American material ends up segregated into a new species or two. Ultimately, the situation requires further study. Below are some photos that I think represent both species.

E. catamarcensis (source observation).

E. serpillifolia (source observation).

Euphorbia amandi
E. amandi (syn. E. minuta Phil. as used by Subils) produces rounded serrated leaves. Currently, there don't seem to be any observations of E. amandi on iNaturalist, but if any show up that I can ID, they will be visible here. As for distinctions, the plant produces serrated leaves which should distinguish it from E. klotzchii, E. serpens, and E. micromera. To distinguish from E. serpillifolia and E. catamarcensis, the key provided by Subils is less helpful. The leaves of E. amandi should be rounder and less elongated, similar to E. klotzchii, E. serpens, and/or E. micromera.

Here, I will keep a list of the links I use to help me identify. I have decided to publish this to help others get a sense of where I am prioritizing my identifications if they're wondering. Since all taxa in sect. Anisophyllum known to occur in both the continental US and Taiwan have now been observed, I'm prioritizing other areas of the world as I have time. Part of my motivation for coming to iNaturalist was to see photos of all species in the section possible. Since that goal is complete in the US and Taiwan, I've decided to refocus my identification efforts. Future activity in those to countries will likely be devoted to select taxa, specific ID requests, and creating identification guides. Antilink here just refers to the opposite conditions of the link specified (e.g., for a link with all observations excluding Texas, the antilink means all observations only in Texas).

Current link for finding species I don't know. (excludes North America, Taiwan, common species, and observations I've added an ID to but don't consider reviewed)
Current most interesting unidentified observations (unfortunately, only I can see these since it only works for my unreviewed specimens)

Everywhere except US: &not_in_place=1
Everywhere except North America: &not_in_place=97394
Everywhere except North America & Taiwan: &not_in_place=97394,7887

US without most common taxa (antilink):
North America without most common taxa (antilink):
&without_taxon_id=58893,58144,200053,58893,200052,275384,200054,131561,131560,148406,275390
US without common taxa:
&without_taxon_id=58893,58144,200053,58893,200052,275384,200054,131561,131560,148406,275390
Euphorbia maculata excluding range of E. humistrata (MN-NB to TX and east in US). (antilink)
Euphorbia maculata excluding range of E. humistrata, E. thymifolia, and E. dioeca (Northern Hemisphere).
Euphorbia maculata excluding range of E. thymifolia and E. dioeca (SouthernHemisphere).
Euphorbia albomarginata excluding range of long appendaged form of E. polycarpa. (antilink)
E. hirta outside of range of E. ophthalmica (last used: 11 Nov 2023) (place_id=7887[Taiwan],6681[India],6903[China],63708[Middle East],7042[Kenya],7144[Tanzania]) (antilink (last used: 11 Nov 2023)).

By Hemisphere
Southern Hemisphere (nelat=0&nelng=-0.0000001&swlat=-80&swlng=0)
Northern Hemisphere (nelat=80&nelng=-0.0000001&swlat=0&swlng=0)
Tropics (between Tropic of Cancer and Tropic of Capricorn) (nelat=23.43632&nelng=-0.0000001&swlat=-23.43632&swlng=0)
Northern subtropics (nelat=35&nelng=-0.0000001&swlat=23.43632&swlng=0)
Southern subtropics (nelat=-23.43632&nelng=-0.0000001&swlat=-35&swlng=0)
Northern temperate (nelat=80&nelng=-0.0000001&swlat=35&swlng=0)
Southern temperate (nelat=-35&nelng=-0.0000001&swlat=-80&swlng=0)
Leftovers (check periodically) (nelat=80&nelng=0&swlat=-80&swlng=-0.0001)

Unreviewed species

Unreviewed observations outside of US
Unreviewed observations within US:

NORTH AMERICA

Caribbean:
Link to most Caribbean areas: https://www.inaturalist.org/observations/identify?nelat=27.10388050060935&nelng=-53.041788354869745&place_id=any&swlat=9.845206918436357&swlng=-85.47342897986974&taxon_id=506796
Including only Islands except northern Venezuela: https://www.inaturalist.org/observations/identify?nelat=27.10388050060935&nelng=-53.041788354869745&place_id=any&swlat=9.845206918436357&swlng=-85.47342897986974&not_in_place=21%2C143141%2C7196&taxon_id=506796

Northern Mexico
https://www.inaturalist.org/observations/identify?place_id=6794,59163,7187,11165,6935,11166,7447,58810,11169,7443&taxon_id=506796

Sonoran:
https://www.inaturalist.org/observations/identify?place_id=6794,59163,7187&taxon_id=506796
Baja Peninsula:
https://www.inaturalist.org/observations/identify?place_id=59163&taxon_id=506796

Chihuahuan:
Strict sense: https://www.inaturalist.org/observations/identify?place_id=11165,6935,11166,7447,58810&taxon_id=506796
Broad sense: https://www.inaturalist.org/observations/identify?place_id=11165,6935,11166,7447,58810,11169,7443&taxon_id=506796
Tamaulipan: https://www.inaturalist.org/observations/identify?place_id=11169,7443&taxon_id=506796

Central Mexico (needs regionalization):
https://www.inaturalist.org/observations/identify?place_id=6793&not_in_place=6794,59163,7187,11165,6935,11166,7447,58810,11169,7443&taxon_id=506796

Euphorbia anthonyi:
https://www.inaturalist.org/observations/identify?nelat=21.66478726453126&nelng=-108.31063722885096&place_id=any&swlat=15.947816028774978&swlng=-116.25375246322596&taxon_id=506796

[CENTRAL AMERICA (AND CENTRAL MEXICO)]
https://www.inaturalist.org/observations/identify?nelat=18.435942554803475&nelng=-76.03234084174059&place_id=any&swlat=6.662532336856699&swlng=-96.75255568549059&taxon_id=506796&not_in_place=8748

SOUTH AMERICA
https://www.inaturalist.org/observations/identify?place_id=97389&taxon_id=506796
[Place IDs: Venezuela (1303); Columbia (7196); Ecuador (7512; -Galapagos: &place_id=7512&not_in_place=12990); Peru (7513); SMALL NORTHERN: Guyana (8142); Suriname (7827); French Guiana (6949); SOUTH CONE: Bolivia (6783); Chile (7182); Paraguay (7254); Uruguay (7259); Argentina (7190); BRAZIL (6878).]

Galapagos:
https://www.inaturalist.org/observations/identify?place_id=12990&taxon_id=506796

Andean:
https://www.inaturalist.org/observations/identify?place_id=1303,7196,7512,7513,6783,7182&not_in_place=12990&taxon_id=506796

South Cone:
https://www.inaturalist.org/observations/identify?place_id=6783,7182,7254,7259,7190&taxon_id=506796

Brazil (needs regionalization):
https://www.inaturalist.org/observations/identify?place_id=6878&taxon_id=506796

EURASIA
https://www.inaturalist.org/observations/identify?place_id=97391,97395&taxon_id=506796

Middle East:
https://www.inaturalist.org/observations/identify?place_id=7183,8207,10299,6815,11730,7055,7833,7358,7837,7356,7359,7357,10284,7355,8206,6818,7351,7352,7346,8435,7341,7076&taxon_id=506796
[Place IDs: Turkey (7183), Syria (8207), Lebanon, (10299), Israel (6815), West Bank (11730), Egypt (7055), Jordan (7833), Saudi Arabia (7358), Yemen (7837), Oman (7356), United Arab Emirates (7359), Qatar (7357), Bahrain (10284), Kuwait (7355), Iraq (8206), Iran (6818), Turkmenistan (7351), Uzbekistan (7352), Kyrgyzstan (7346), Tajikistan (8435), Afghanistan (7341), Pakistan (7076)]

India:
https://www.inaturalist.org/observations/identify?place_id=6681,7335,7707,7154&taxon_id=506796
[Place IDs: India (6681), Nepal (7335), Bhutan (7707), Bangladesh (7154)]

Southeast Asia:
https://www.inaturalist.org/observations/identify?place_id=6992,6967,7155,7001,7002,6847&taxon_id=506796
[Place IDs: Myanmar (Burma) (6992), Thailand (6967), Malaysia (7155), Laos (7001), Cambodia (7002), Vietnam (6847)]

China, Taiwan, Japan, etc.:
https://www.inaturalist.org/observations/identify?place_id=6903,7347,7887,6737,8432,6891&taxon_id=506796
-Taiwan: https://www.inaturalist.org/observations/identify?place_id=6903,7347,6737,8432,6891&taxon_id=506796
[Place IDs: China (6903), Mongolia (7347), Taiwan (7887), Japan (6737), North Korea (8432), South Korea (6891)]

[MEDITERRANEAN REGION]
https://www.inaturalist.org/observations/identify?place_id=53832&taxon_id=506796

AFRICA
https://www.inaturalist.org/observations/identify?place_id=97392&taxon_id=506796
Without Madagascar and adjacent islands: https://www.inaturalist.org/observations/identify?place_id=97392&not_in_place=7783,10306,8421,9319,8834,8357,8358&taxon_id=506796

Flora of Tropical East Africa
https://www.inaturalist.org/observations/identify?place_id=7144,7106,7142,6968,7042&taxon_id=506796
[Place IDs: Tanzania (7144), Burundi (7106), Rwanda (7142), Uganda (6968), Kenya (7042)]
Flora Zambesiana
https://www.inaturalist.org/observations/identify?place_id=7145,7113,7134,7146,7105,97120&taxon_id=506796
[Place IDs: Zambia (7145), Malawi (7113), Mozambique (7134), Zimbabwe (7146), Botswana (7105), Zambezi (Namibia; 97120)]

INDIAN OCEAN (working)
https://www.inaturalist.org/observations/identify?place_id=7783,10306,8421,9319,8834,8357,8358,10800,8425,10295,7077,7616,10287,12515,10293,48150,121020&taxon_id=506796
Working region: https://www.inaturalist.org/observations?nelat=21.105143486959374&nelng=91.92773937756704&swlat=-45.35203736790343&swlng=33.65625500256704
Geographic outer bounds including large parts of adjacent continents: https://www.inaturalist.org/observations?nelat=26.198396817403204&nelng=148.13726187471735&place_id=any&swlat=-70.37280992210458&swlng=18.289523026860213

Arabian Islands (i.e., Socotra; may expand):
https://www.inaturalist.org/observations/identify?nelat=13.141003126359843&nelng=56.828155517578125&place_id=any&swlat=11.66568597420363&swlng=51.606903076171875
[Place IDs: Qulensya Wa Abd Al Kuri (48150), Socotra (121020)]

Madagascan Islands:
https://www.inaturalist.org/observations/identify?place_id=7783,10306,8421,9319,8834,8357,8358&taxon_id=506796
[Place IDs: MADAGASCAR (7783): Mayotte (10306) Comoros (8421), !French Southern Territories (9319), Reunion (8834), Mauritius (8357), Seychelles (8358)]

Indian Islands:
https://www.inaturalist.org/observations/identify?place_id=10800,8425,10295,7077&taxon_id=506796
[Place IDs: Lakshadweep (India; 10800), Maldives (8425), British Indian Ocean Territory (10295), Sri Lanka (7077)]

Indonesian adjacent:
https://www.inaturalist.org/observations/identify?place_id=7616,10287&taxon_id=506796
[Place IDs: Christmas Island (7616), Cocos Islands (10287)]

South Indian Islands:
https://www.inaturalist.org/observations/identify?place_id=12515,9319,10293&taxon_id=506796
[Place IDs: Prince Edward Islands (12515), !French Southern Territories (9319), Heard Island and McDonald Islands (10293)]

OCEANIA+INDONESIA
General: https://www.inaturalist.org/observations/identify?place_id=97393&taxon_id=506796
Without Australia, New Zealand, New Guinea, Hawaii, and US Territories: https://www.inaturalist.org/observations/identify?place_id=97393&not_in_place=6744,6803,7013,6966,11,10316&taxon_id=506796
[Place IDs: Australia (6744), New Zealand (6803), Indonesia (6966), Papua New Guinea (7013), Philippines (6873), Malaysia (7155)]

Indonesia+
https://www.inaturalist.org/observations/identify?place_id=6966,7013,6873,7155&taxon_id=506796

Australia
https://www.inaturalist.org/observations/identify?place_id=6744&taxon_id=506796

Hawaii:
https://www.inaturalist.org/observations/identify?place_id=11&taxon_id=506796
Hawaii+: https://www.inaturalist.org/observations/identify?place_id=11,10316&taxon_id=506796
[Place IDs: Hawaii (11), United States Minor Outlying Islands (10316)]

ATLANTIC OCEAN (EXCLUDING CARIBBEAN)
General: https://www.inaturalist.org/observations/identify?place_id=8638,13197,7291,80273,9445,6685,23799,20937,7690,7985&taxon_id=506796
Islands with endemics: https://www.inaturalist.org/observations/identify?place_id=6685&taxon_id=506796

North Atlantic:
https://www.inaturalist.org/observations/identify?place_id=8638,13197,7291,80273,9445&taxon_id=506796
[Place IDs: NORTH AMERICAN: Bermuda (8638); AFRICAN/EUROPEAN: Azores (13197), Madeira (7291), Islas Canarias (80273), Cape Verde (9445)]

South Atlantic:
General: https://www.inaturalist.org/observations/identify?place_id=6685,23799,20937,7690,7985&taxon_id=506796
Endemics: https://www.inaturalist.org/observations/identify?place_id=6685&taxon_id=506796
[Place IDs: Saint Helena: (6685), SOUTH AMERICAN: Fernando de Noronha (23799), Ilha Trindade (20937); SOUTH AMERICAN/ANTARCTIC: Falkland Islands (7690), South Georgia and the South Sandwich Islands (7985)]

Observations with an identification of a sandmat:
https://www.inaturalist.org/observations/identify?ident_taxon_id=50679

Common Euphorb identifiers or experts (Euphorbia; working list):
Knowledgeable power-identifier's usernames: trh_blue, janeyair
Recognized Euphorbia experts' usernames: vicsteinmann [Euphorbia; Mexico and South America], spurgeckr [Poinsettia, Tithymalus, Anisophyllum; North America], dmitrygeltman [sect. Esula, subg. Esula in Russia?], edwinbridges [US Nummulariopsis]

Expert identifications for reference (Euphorbia):
https://www.inaturalist.org/observations/identify?taxon_id=51822&ident_user_id=vicsteinmann,spurgeckr,dmitrygeltman,edwinbridges

Knowledgeable power-identifier:
https://www.inaturalist.org/observations/identify?taxon_id=51822&ident_user_id=trh_blue,janeyair,jrebman
janeyair review observation
trh_blue review observations: 80-90% confidence
trh_blue review observations: 60-80% confidence
trh_blue review observations: 20-60% confidence
Without IDs:
https://www.inaturalist.org/observations/identify?taxon_id=51822&ident_user_id=trh_blue,janeyair,jrebman

Searching Broadly:
Anisophyllum (without species-level ID): https://www.inaturalist.org/observations/identify?taxon_id=506796&lrank=section
Chamaesyce (without section-level ID): https://www.inaturalist.org/observations/identify?lrank=subgenus&taxon_id=792275
Euphorbia (without subgenus-level ID): https://www.inaturalist.org/observations/identify?lrank=genushybrid&taxon_id=51822
Euphorbiaceae (without genus-level ID): https://www.inaturalist.org/observations/identify?lrank=subtribe&taxon_id=51821
Malpighiales (without family-level ID): https://www.inaturalist.org/observations/identify?lrank=epifamily&taxon_id=51820
Dicots (without order-level ID): https://www.inaturalist.org/observations/identify?lrank=superorder&taxon_id=47124
Plants (without class-level ID): https://www.inaturalist.org/observations/identify?lrank=superclass&taxon_id=47126
Plants (without genus-level) that have an Anisophyllum ID: https://www.inaturalist.org/observations/identify?taxon_id=47126&lrank=subtribe&ident_taxon_id=506796

Peplis Clade
Sand clade:
Identify
Explore
[E. geyeri var. geyeri: 314585; E. geyeri var. wheeleriana: 314584; E. bombensis: 131559; E. cordifolia: 202340; E. cumulicola: 505195; E. carunculata: 275375; E. platysperma: 275399; E. incerta: 275385; E. polygonifolia: 203695; E. missurica: 474008; E. parryi: 148411; E. peplis: 334741; E. glaucophylla: 1013585]
Fendleri clade:
Identify
Explore
[E. crepitata var. crepitata: 314580; E. crepitata var. longa: 314581; E. crepitata: 273725; E. chaetocalyx var. chaetocalyx: 314578; E. chaetocalyx var. triligulata: 314579; E. chaetocalyx: 273724; E. cryptorubra: 502566; E. golondrina: 275382; E. fruticulosa var. fruticulosa: 314582; E. fruticulosa var. hirtella: 314583; E. fruticulosa: 273726; E. perennans: 275395; E. simulans: 275405; E. theriaca var. theriaca: 314599; E. theriaca var. spurca: 314600; E. theriaca: 273731; Tentative placement: E. scopulorum: 273729; E. scopulorum var. inornata: 314594; E. scopulorum var. nuda: NA; E. scopulorum var. scopulorum: NA]
Unplaced:
[E. scopulorum: 273729; E. scopulorum var. inornata: 314594; E. scopulorum var. nuda: NA; E. scopulorum var. scopulorum: NA; E. ocellata: 473570; E. ocellata var. ocellata: 506216; E. ocellata var. rattanii: 506218; E. ocellata var. arenicola: 506217; E. parishii: 474004]
Chihuahuan clade:
Identify
Explore
[ : ; : ; : ; : ; : ; : ; : ; : ; : ; : ;]
Wire clade:

Identify
Explore
[ : ; : ; : ; : ; : ; : ; : ; : ; : ; : ;]
Sonoran 2 clade:
Identify
Explore
[ : ; : ; : ; : ; : ; : ; : ; : ; : ; : ;]
Sonoran 1 clade (excluding putative hybrids with E. serpens):
Identify
Explore
[ : ; : ; : ; : ; : ; : ; : ; : ; : ; : ;]

Base format:
https://www.inaturalist.org/observations/identify?place_id=&taxon_id=506796
[Place IDs: ]
Flora
https://www.inaturalist.org/observations?place_id=any&taxon_ids=

Test for compare function:
E. fendleri map 1
Map 2
Map 3
Observation field: https://www.inaturalist.org/observation_fields/7945
E. antisyphilitica
Sanddune clade
Chihuahuan Desert endemic clade

Density gradient maps

Density gradient map for sect. Anisophyllum
Density gradient map for sect. Anisophyllum without most commonly observed species (antilink)
Density gradient map for sect. Anisophyllum without most commonly observed species (species level IDs only)
Density gradient map for Euphorbia

Species complexes

E. porteriana s.l.
&taxon_id=505202%2C1287102%2C487616%2C1352310
Big Pine Key morphotypes ([garberi][ogdenii])
&nelat=24.818625440044084&nelng=-81.16851148084105&swlat=24.568374738648096&swlng=-81.58599186577202
Duck Key morphotypes ([garberi, ogdenii])
&nelat=24.804258796032535&nelng=-80.85893009809644&swlat=24.581766929691206&swlng=-81.14944788995614
Layton Key morphotypes ([ogdenii])
&nelat=25.08159771267202&nelng=-80.67741456907243&swlat=24.80169318348145&swlng=-81.03401542487363
Key Largo morphotypes ([porteriana])
&nelat=25.348268090743897&nelng=-80.22135751239936&swlat=25.03698077967577&swlng=-80.54414432438224
Mainland
&nelat=26.570999373312954&nelng=-80.36826768679828&swlat=25.212058619927745&swlng=-85.11985426558465

E. fendleri complex

E. fruticulosa group
Coahuila core: place_id=101545,101502,101583

• place_id=101545,101502,101583,101568,36657,36648,37336,101581
  place_id=101545 (Cuatro Ciénegas), 101502 (Francisco I. Madero, CP),101583 (San Pedro, CP), 101568 (Matamoros, CP),36657 (Lerdo, DU),36648 (Cuencamé, DU),37336 (Mina, NL),101581 (Ramos Arizpe)
  Possible extras

• ,101561,101578
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  Last reviewed 16 Sep 2023

It's taken longer than it should have, but I have now finished adding all the species known to be in sect. Anisophyllum to the sect. Anisophyllum taxon in iNaturalist. This means that you can now view the names of all the species in the section by simply looking at the taxon profile page: https://www.inaturalist.org/taxa/506796-Anisophyllum
There are still some synonymy issues for a few species that I'll have to look into at some point, but this should be more than enough until more observations start coming in from the regions that have the aforementioned species.

The next step would be to try to add in the ranges for all of these, but I'm not sure I'll ever get around to doing that. What I'm trying to focus on more is finding what species have been photographed and which haven't in order to focus outreach efforts on geographic regions with high numbers of species without photos (that is, when I'm not focusing on Ph.D. work or can find a way to tie it into Ph.D. work).

Also, all Euphorbia species that have been recognized at section level by Euphorbia PBI (www.euphorbiaceae.org) have now been grafted into their respective section in iNaturalist except for the following sections:
Esula (6 taxa to add; 36 species to add to section)
Helioscopia (6 taxa to add; 45 species to add to section)
Euphorbia (34 taxa to add; 174 species to add to section)
Monadenium (1 species to add; 61 species to add to section)

This doesn't include the many synonymy contradictions nor the very likely possibility that I made mistakes. Also, not all Euphorbia species are known to section level yet. That said, if anyone wants to finish up what I started, these last four sections are the largest and most time-consuming taxa to change (except sect. Anisophyllum, which I took care of). The help would be much appreciated (@trh_blue, want another project :-)). After this is done, it will be a matter of looking at the remaining ungrafted species in Euphorbia to see if they or their synonyms are recognized at section or subgenus level. I doubt all will ever be fully grafted as the taxonomy isn't fully known yet, but we can get a lot of the way there.

This has been an awesome Euphorbia year for iNaturalist and I figured I'd share the highlights with all of you. Firstly, we broke 20,000 observations of Euphorbia sect. Anisophyllum! This is amazing for such a small underappreciated group of plants. We also got to 160 species! This is an awesome number and way more than I ever could have dreamed when I first looked into iNaturalist in 2014. Believe it or not, this is still well under half the number of total species known. My last count going through my excel datasheet yielded about 404 valid species with 488 taxa (i.e., including subspecific entities). Some places, in particular, have witnessed amazing growth in the past year and I'd like to highlight that by discussing what's going on by continent:

North America: With the uploading of E. laredana this year, there are only 3 species left in the continental United States that have not been observed there. Since these species have been observed in Mexico, all species that occur in the continental US have now been photographed. I have not tallied the species for Mexico, but there are definitely species left to be photographed there. As for my personal research, this has been a great year with leaps forward in the E. dioeca complex, E. adenoptera complex, E. serpillifolia complex, and understanding the Baja California endemics. I highly recommend looking through some of the Baja California observations. They represent a group of species that are difficult to nearly impossible to define without seeds, but quite interesting and beautiful. There were a lot of interesting observations posted, but many are potentially publishable finds so I don't want to go into a ton of details here. I would like to thank @jaykeller, @gilles48, @catchang, @jrebman, @susanhewitt, and @mjplagens for these and other many wonderful observations and commentary! As the continent that has produced 83.9% of the total sect. Anisophyllum observations and has 82.1% of the total sect. Anisophyllum observers worldwide, there are so many more observers here that should be thanked, but time prohibits me from listing them all. I will also be writing shorter yearly highlights for the Euphorbia species of the United States and probably Euphorbia of Mexico, so hopefully I will have the chance to make up for this lack.

South America: A lot of awesome observations came in this year from South America! In particular, Columbia and Ecuador have taken off. Because of this, I've had the opportunity to attempt IDs for species from the Galapagos and the Andes! All the Galapagos endemics are shrubby species that are very closely related and even hybridize with each other. For a species that will amaze you, I recommend looking at E. amplexicaulis Despite how weird and wonderful they are, I personally prefer studying the opaque mystery of the Andean endemics. The species are all closely related, poorly studied and seem relatively poorly defined. My favorites are E. jamesonii and E. melanocarpa. There was also a good burst in Paraguay were species like E. eichleri and E. oranensis were observed. I have a particular fondness for E. oranensis as it looks like some strange cross between E. prostrata and E. stictospora. As for my research, the observations of E. ophthalmica, E. adenoptera, and E. dioeca have been immensely interesting and/or helpful. Thanks especially to @patrickas, @elacroix-carignan, @ripleyrm, and @profe_mire.

Europe: Not much to report out of Europe this year for E. sect Anisophyllum. The E. peplis and E. chamaesyce observations are always wonderful, but well known. Euphorbia peplis is a particularly interesting species as it is the type species for the genus Chamaesyce and has what I think are the most asymmetric leaves of any species in the section. Euphorbia chamaesyce is interesting because its specific epithet is that of the genus. Because of this, the name under the genus Chamaesyce is different (C. canescens). I'm really hoping someone finds the only endemic taxon to the continent: Euphorbia serpens var. fissistipula. This is a really nice plant and one of the few that has a well defined pistillate calyx.

Asia: I have been super excited about the handful of observations that have come out of India. I consider these to be some of the most beautiful in the world and rival even the showy appendages of some of the Sonoran Desert species! I am especially grateful for the observations by @swapnaprabhu, @aparnaw, @mayuresh_kulkarni, @sushantmore, and @chiefredearth. Though not on iNaturalist, Euphorbia cristata yet continues to be my favorite from the continent, though Euphorbia kischenensis may be a close second. I even joined efloraofindia to facilitate my understanding of these species. Taiwan continues to be a reliable source of observations and I think most or all of the species were observed here last year (I'll check this next time I look into the group for the region). In Taiwan, I am particularly appreciative of all the observations contributed by @pseudoshuigeeee. A review of Asia wouldn't be complete without mentioning the high-quality observations @trh_blue and @trcarlisle have been posting from the western Middle East (Israel and mostly Turkey respectively). Though there are fewer endemic Anisophyllous species in these regions than other areas in Asia, these two have provided one of the most consistent supplies of high-quality observations across the continent outside of Taiwan.

Africa: I admit to being a bit less active here than I'd like to be. There are several African endemics that have been observed, but most are represented by the following trans-continental species: E. hyssopifolia, E. hirta, E. ophthalmica, E. serpens, E. prostrata, E. hirta, E. thymifolia, and E. maculata. A couple of the more interesting species posted are Euphorbia neopolycnemoides and Euphorbia convolvuloides. Euphorbia ophthalmica has some interesting variability in Africa that indicates it may have originated from separate New World populations. I have been more active in identifying the species in Madagascar and the surrounding islands. Euphorbia mertonii is a beautiful little plant. @jpcasti has kindly provided photos from Reunion outside of iNaturalist. @ehbidault has provided photos from other surrounding islands. To both, I am quite grateful. As for the rest of Africa, I really hope to do more next year as there are some quite interesting forms that have been observed there.

Australia and the rest of Oceania: Australia has witnessed an uptick in observations this year. Relative to the very high diversity of endemics found in Australia, there still aren't many on here yet, but I'm hopeful for next year. I'm particularly fond of the new observations of Euphorbia wheeleri and Euphorbia ferdinandi var. ferdinandi. I especially appreciate the contributions of @silversea_starsong, @williamdomenge9, @nyoni-pete that have proved quite memorable. Hawaii continues to do pretty well as I continue to put off looking into their identifications. I think this is the only place on earth were the species in this group become trees. There are no observations really showing this, but this observation of Euphorbia celastroides var. kaenana shows just how woody these plants can get. New Zealand has been observed abundantly but seems to only have one known species: E. maculata, a common weedy plant worldwide. There are few observations in Oceania outside Australia, New Zealand, and Hawaii but they are interesting. Those that aren't the common intercontinental species are mostly represented by species often referred to as E. atoto or are related to these. I have been hesitant to get into this group as E. atoto itself generally refers to the wrong plant when commonly applied (more information here). Here's an interesting member of this group observed this year that isn't E. atoto.

Overall, it appears my New Year's resolution needs to be to focus on the species from continental Africa, Hawaii, and the Oceanian members commonly referred to as E. atoto. In addition to this, there are several species complexes in North America that need revision. It appears a taxonomists work is never done! Hope everyone had a Happy New Year and here's to a good year of study and observing Chamaesyces!

All 35 taxa known to occur in India have been added. The full list can be found here. Species on efloraofindia can be found here.

I'm starting to go through continent by continent and add all the species of Anisophyllum that haven't been added here yet. Just got finished with Australia (click here for the full list).

Overall, Australia has 87 taxa and 58 species. Queensland and the Northern Territory are tied for the regions having the most taxa at 49 a piece (Western Australia has 48).

What follows is a list of species within sect. Anisophyllum from Madagascar. Many of the links are only accessible if you have access to JSTOR Plants. I'll try to switch over to more open-source platforms as I get into it more. Sources: Euphorbia PBI data portal; JSTOR Plants; Muséum National D'Histoire Naturelle (P). Specimens at GBIF.

Euphorbia grandidieri Baill.
Bull. Mens. Soc. Linn. Paris 1:615, 1886
Euphorbia PBI data, Holotype, Specimens at GBIF.

Euphorbia hirta L.
Sp. Pl. 454, 1753

Euphorbia humbertii Denis
Euphorb. Iles Austr. Afr. 28, 1921
Euphorbia PBI data, Holotype, Specimens at GBIF.

Euphorbia hypericifolia L.
Sp. Pl. 454, 1753

Euphorbia hyssopifolia L.
Syst. Nat. ed. 10, 2:1048, 1759

Euphorbia mertonii Fosberg
Kew Bull. 33:181, 1978
Euphorbia PBI data, Holotype, Specimens at GBIF.
http://www.tropicos.org/Specimen/100907931

Euphorbia pellegrinii Leandri
Notul. Syst. (Paris) 13:113, 1947
Euphorbia PBI data, Holotype, Specimens at GBIF.

Euphorbia thymifolia L.
Sp. Pl. 454, 1753

Euphorbia trichophylla Baker
J. Linn. Soc., Bot. 20:250, 1883
Euphorbia PBI data, Type, Specimens at GBIF.

Euphorbia vezorum Leandri
Notul. Syst. (Paris) 13:116, 1947
Euphorbia PBI data, Holotype (no photo), Specimens at GBIF.

Stats updated 30 Dec 2021 unless stated otherwise
New observations per year:
2010: 1
2011: 7 (total: 8)(x7)
2012: 20 (total: 28)(x2.86)
2013: 82 (total: 110)(x4.1)
2014: 185 (total: 295)(x2.26)
2015: 671 (total: 966)(x3.63)
2016: 1,306 (total: 2,272)(x1.95)
2017: 3,251 (total: 5,523)(x2.49)
2018: 7,697 (total: 13,345)(x2.37)
2019: 11,166 (total: 24,605)(x1.45)
2020: 15,995 (total: 40,805)(x1.43)
2021: 20,099 (total: 61,083)(x1.26)

New species per year:
2010: 1
2011: 6 (total: 5)
2012: 8 (total: 13)
2013: 19 (total: 32)
2014: 19 (total: 52)
2015: 27 (total: 79)
2016: 15 (total: 94)
2017: 21 (total: 115)
2018: 25 (total: 140)
2019: 20 (total: 160)
2020: 26 (total: 186)
2021: 19 (total: 205)

All observations

Species
Euphorbia abramsiana
Euphorbia apicata
Euphorbia albomarginata
Euphorbia arizonica
Euphorbia bartolomaei
Euphorbia brandegeei
Euphorbia capitellata
Euphorbia "geminiloba": ob. 1, ob. 2, ob. 3.
Euphorbia cerralvensis
Euphorbia chamberlinii
Euphorbia dentosa
Euphorbia dioeca
Euphorbia hirta
Euphorbia hyssopifolia
Euphorbia incerta
Euphorbia leucophylla
Euphorbia leucophylla ssp. leucophylla
Euphorbia leucophylla ssp. comcaacorum (Sonora only)
Euphorbia maculata
Euphorbia magdalenae
Euphorbia melanadenia
Euphorbia micromera
Euphorbia pediculifera
Euphorbia pediculifera var. pediculifera
Euphorbia pediculifera var. linearifolia
Euphorbia pediculifera (taluticola maculations)
Euphorbia peninsularis
Euphorbia petrina: Patrick Alexander photos
Euphorbia polycarpa
Euphorbia polycarpa var. carmenensis
Euphorbia polycarpa var. johnstonii
Euphorbia polycarpa var. mejamia
Euphorbia polycarpa var. polycarpa
Euphorbia polycarpa var. intermixta (placeholder name only)
Euphorbia polycarpa morphotype 1 (placeholder only)
Euphorbia pondii
Euphorbia serpens
Euphorbia serpillifolia
Euphorbia setiloba
Euphorbia taluticola
Euphorbia tomentulosa
Euphorbia trachysperma
Euphorbia vizcainensis

Southern Islands
All observations
Euphorbia anthonyi: morphotype 1 (Isla Clarión), morphotype 2 (Isla San Benedicto; Type locality), morphotype 3 (Isla Soccoro).
Euphorbia incerta

var.

Section Anisophyllum explained
What makes a good sandmat observation?
Project statistics

iNaturalist projects:
Euphorbia species of the United States
Euphorbia of Mexico
Sandmats of the World

General recomended external links:
Flora of North America
BONAP (for maps)
Euphorbia PBI
Euphorbia PBI species search
Tropicos (great way to find primary literature sources)
Biodiversity Heritage Library (great way to find primary literature sources)
GBIF (great way to find herbarium records)
Encyclopedia of life (often useful if you can find a good global map)
SEINet (great way to find herbarium records and photos)
Index herbariorum (useful in understanding what the herbarium abbreviations refer to)

United States state specific resources (not comprehensive and in progress)
California:
Jepson eFlora
Calflora
Florida:
Florida Euphorbia species
Atlas of Florida Plants
New Mexico:
The status of the genus Chamaesyce in New Mexico
Texas:
The Weedy Species of Sandmats (Euphorbia sect. Anisophyllum) in Texas
Sandmats (Euphorbia sect. Anisophyllum, previously Chamaesyce) of the Llano Estacado
Australia
Seeds of South Australia
Japan
Weeds of Japan
Iran
Seed and gland morphology in Euphorbia (Euphorbiaceae) with focus on their systematic and phylogenetic importance, a case study in Iranian highlands
Seed morphology of Iranian annual species of
Euphorbia (Euphorbiaceae)
North American list of species (essentially complete)
South American list of species (essentially complete)
Eurasian list of species (not yet available)
African list of species (not yet available)
Australian list of species (essentially complete)
Pacific Islands list of species (not yet available)
Indian Ocean Islands list of species (not yet available)
Atlantic Islands list of species (not yet available)