VARIATION IN THE CHRISTMAS FERN, POLYSTICHUM ACROSTICHOIDES

NOTES: Section 1 was revised and reposted on 12 January 2021. Section, MINIATURE CHRISTMAS FERNS, is retained below.

I submit to iNaturalist members the following information in the hopes that enthusiast will investigate and report upon the variation of Christmas Ferns, Polystichum acrostichoides, in their regions.

I know not how to coordinate any such effort, and encourage those who can manage that feat to do so. Pick up the baton and run, so to speak.

The magnitude of the task of investigating thoroughly the populations of Christmas Ferns across this species vast natural distribution is an insuperable undertaking for one person. It is hoped that many hands will make light work. All credit should go to those who participate.

Cheers to you all,
Michael Papay.


SECTION 1.

The Christmas Fern, Polystichum acrostichoides, in the un-glaciated lower Piedmont and Triassic basin of North Carolina, exhibits the diversity of color and form indicated below. What variation is to be found in previously glaciated realms where this species now occurs. Are populations in previously un-glaciated regions more diverse? Less diverse? Differently diverse? iNaturalist members in eastern North America, the natural realm of Polystichum acrostichoides, can investigate the variation in their Christmas Fern populations, and post photos and info at iNaturalist.

COLOR FORMS
(1) solid medium green;
(2) solid light green;
(3) solid blue-green;
(4) bicolor
- green & blue-green: center-line of leaflet is green whilst margin is blue-green;
- bright edge: green with a highly contrasting light green edge.
PHYSICAL FORMS
(1) EDGES (leaflets/pinnae)
- very shallowly serrated leaflet margin;
- shallow-lobed leaflet margin;
- fully lobed: leaflet subdivided into sub-leaflets;
- twice divided leaflets: leaflets divided into lobes which themselves are lobed;
- crested/fasciated leaflets - edges terminate in multiple divisions, sometimes bizarrely so.
(2) PLANE (leaflets/pinnae)
- leaflets straight-ish;
- leaflets distinctly curved;
- leaflets undulate.
(3) LENGTH (leaflets/pinnae)
- leaflets short
- leaflets usual
- leaflets long
(4) WIDTH (leaflets/pinnae)
- leaflets narrow
- usual
- wide
(5) TIP (of leaflet/pinnae)
- tapered to a single narrow point – usual case for mature plants.
- rounded; not narrowly pointed – all young plants, uncommon in mature plants
- divided into two (or more) points (crested) – more common in miniature forms.
(6) FROND LENGTH, PLANT SIZE:
- miniature fronds: plants fertile when small, remain small in old age, often crested [see study below].
- usual frond length
- longer fronds, larger plants
(7) FROND ASPECT
- fronds variously upright to lateral
- fronds mostly upright
- fronds displayed laterally

Each color form may exhibit each physical form. Each physical form may combine with other physical forms. The potential diversity is staggering. When one form is found, permutations are often nearby.


SECTION 2.

MINIATURE CHRISTMAS FERNS – A STUDY, By Michael J. Papay, 18 December 2020

I have observed miniature Christmas Ferns, Polystichum acrostichoides, amongst local (Raleigh, North Carolina vicinity) natural populations. The miniature forms are distinguishable by: (1) their small frond size; (2) by their leaflets (pinnae) being smaller versions of plants of usual dimensions and specifically not the very rounded leaflets (pinnae) of young plants; (3) presence of fertile fronds; (4) formation of clonal clump via branching of the rhizome. https://www.inaturalist.org/observations/66415436

I conducted a study that included 13 miniature Christmas Ferns with at least 3 fertile fronds each, and 15 randomly selected usual Christmas Ferns with at least 3 fertile fronds each. To assure that small plants were not simply young plants, only plants from clonal clumps produced by rhizomatous branching were included in the study. For each study plant, the longest 3 fertile fronds were measured. All plants occurred in-situ in the wild. Two sites, several miles apart, were visited. Each site had miniature and usual forms in the landscape. Plants were measured at the end of the growing season, on 03 and 08 December 2020. The data are presented below. Fertile Frond Measurements (FFM) are to the nearest sixteenth of an inch.


Table 1. Fertile Frond Measurements of Miniature and Usual plants of
Christmas Fern, Polystichum acrostichoides


MINIATURE

Plant FFMs

1 14.17, 14.00, 14.25

2 15.35, 21.85, 18.62

3 20.86, 18.62, 18.97

4 15.03, 14.37, 14.01

5 16.75, 18.50, 20.50

6 10.31, 11.50, 10.37

7 14.75, 14.75, 14.5

8 17.00, 15.50, 14.25

9 16.26, 16.00, 14.25

10 10.25, 9.37, 8.5

11 11.00, 11.12, 10.37

12 8.69, 8.12, 6.00

13 13.56, 13.25, 13.00

n = 39

average (Xm) = 14.064
standard deviation (SDm) = 3.862

SDm squared (SDm2) = 13.557

USUAL
Plant FFM’s
1 25.62, 21.50, 24.87
2 30.12, 30.37, 32.00
3 25.62, 28.25, 29.25
4 20.12, 21.75, 22.12

5 30.12, 30.00, 30.06
6 25.12, 25.25, 25.00
7 29.50, 29.25, 29.12
8 31.75, 31.56, 31.50
9 21.00, 17.00, 20.25
10 26.25, 26.50, 26.25
11 26.25, 26.87, 23.12
12 23.37, 25.12, 21.00
13 26.50, 25.56, 27.00
14 25.12, 25.50, 24.00
15 29.00, 27.50, 27.00

n = 45
average (Xu) = 26.222
standard deviation (SDu) = 3.507

SDu squared (SDu2) = 12.299

The two-sample standardized test statistic, Z, was used to test the Null Hypothesis that there is no difference between the average fertile frond lengths of miniature versus usual plants of Christmas Fern. The “one-sided” Alternative Hypothesis chosen was that miniature plants on average have smaller fertile fronds than usual plants of Christmas Fern. A 95% confidence interval was selected for testing, giving a Z value of -3.9 based on a one-sided Standard Z Test Statistic Table. Thus, if the calculated value of the test statistic Z is less than -3.9, the 95% confidence interval is reached and the Null Hypothesis is rejected in favor of the Alternative Hypothesis.
Test statistic Z = [(Xm – Xu) – 0] divided by the square root of [SDm2/39 + SDu2/45].
Z = [(14.064 – 26.222)/square root (13.557/39 + 12.299/45)] = -15.43. The Null Hypothesis is rejected with 95% confidence. The Alternative Hypothesis is accepted, that on average the fertile fronds of miniature Christmas Ferns are significantly shorter than the fertile fronds of usual Christmas Ferns.


This study does not resolve what may be the cause of the miniature size.

פורסם על-ידי mjpapay mjpapay, דצמבר 31, 2020 12:40 לפנה"צ

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mjpapay

תאריך

נובמבר 29, 2020 10:16 AM EST

תיאור

Miniature Form: Polystichum acrostichoides 'nana'

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מתצפת/ת

mjpapay

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נובמבר 27, 2020 10:46 AM EST

תיאור

Miniature Form: Polystichum acrostichoides 'nana'

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מתצפת/ת

mjpapay

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ינואר 9, 2021 10:04 AM EST

תיאור

Clonal colony of a miniature Christmas Fern. The miniature versions have been observed throughout the local area. Infrequent as a rule, but when one is found others are usually nearby.