VARIATION IN POLYSTICHUM ACROSTICHOIDES

NOTICE: This journal page - Variation in Polystichum acrostichoides - is released from copyright restriction of the author, Michael Papay (mjpapay iNaturalist) so that it may be copied, modified, and made use of by other iNaturalist members who wish to document variation in Polystichum acrostichoides in their region, or wish to adapt this page for documentation of variation in other taxa. Michael Papay (mjpapay iNaturalist) 26 January 2021.

NOTE: This journal post replaces that of 10 January 2021, whose errors were corrected. Also, a few links have been added or replaced. MOST RECENT UPDATE: 29 January 2021.

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. erwin_pteridophilos (@erwin_pteridophilos) advised that the source of the variation may at least in part be due to the expression (phenotypic re-emergence) of ancestral genes. This appears to be corroborated by observations of individual Polystichum acrostichoides with completely separate fertile fronds (unlike the usual situation in Polystichum acrostichoides where the fertile section is located at the end of an otherwise sterile frond), and in individuals with twice-divided fronds (unlike the usual once-divided fronds of this species).

What variation occurs in previously glaciated realms? Are populations there more diverse? Less diverse? Differently diverse?

I have not encountered (observed) individuals with long, wide pinnae (leaflets) outside of the Triassic Basin, and then only in lowland mesic areas. They are absent (or scarce?) in adjacent uplands where usual forms still abound.

LEAFLET COLOR
(1) Green https://www.inaturalist.org/observations/67675217
(2) Darkest Green https://www.inaturalist.org/observations/67971542
(3) Blue-green https://www.inaturalist.org/observations/67326452
(4) Bicolor
a. Blue-Green blade with green central vein https://www.inaturalist.org/observations/66442425
b. Bright Edge https://www.inaturalist.org/observations/67855800

PHYSICAL FORMS OF LEAFLETS
(1) EDGES
a. Shallow Serration https://www.inaturalist.org/observations/67326452
b. Shallow-Lobe https://www.inaturalist.org/observations/67538429
c. Lobed https://www.inaturalist.org/observations/67673243
d. Twice Divided, lobes which themselves are lobed https://www.inaturalist.org/observations/66804039
e. crested/fasciated leaflets, edges terminate in multiple divisions https://www.inaturalist.org/observations/67855570
(2) PLANE
a. Straight-ish; usual https://www.inaturalist.org/observations/67807301
b. Curved, sometimes doubly so (recurved) https://www.inaturalist.org/observations/67537716
c. Undulate (“crisped” in old parlance) https://www.inaturalist.org/observations/67634628
(3) LENGTH
a. Short: less than 2 inches https://www.inaturalist.org/observations/67854694
b. Usual: about 2 inches (5 cm) long https://www.inaturalist.org/observations/67675217
c. Long: much longer than 2 inches https://www.inaturalist.org/observations/67673345
(4) WIDTH
a. Usual: leaflets about 3/8ths inch (1 cm) wide when 2 inches (5 cm) long https://www.inaturalist.org/observations/67872751
b. Narrow (relative to length) https://www.inaturalist.org/observations/67312460
c. Wide relative to length https://www.inaturalist.org/observations/67544636
(5) TIP
a. Acute, pointed – usual case for mature plants https://www.inaturalist.org/observations/67673345
b. Blunt, rounded – all young plants https://www.inaturalist.org/observations/67311024 https://www.inaturalist.org/observations/67156829
c. Divided, also called “crested” https://www.inaturalist.org/observations/67673880
(6) EAR, auricle: located near the stem-side of the leaflet.
6a. Acroscopic: on upper edge of leaflet and points toward the stem tip - usual condition.
i. Short - wider than tall https://www.inaturalist.org/observations/67591938
ii. Usual - about as tall as wide
iii. Tall - taller than wide https://www.inaturalist.org/observations/67538230
iv. Separate - as a lobe, usually restricted to lower (basal) leaflets https://www.inaturalist.org/observations/67592332
6b. Basioscopic: on lower edge of leaflet and points toward base of stem https://www.inaturalist.org/observations/68624358
(7) GAP (between adjacent leaflet edges)
a. Slight gap, usual https://www.inaturalist.org/observations/67591938
b. Wide gap https://www.inaturalist.org/observations/67635552
c. Overlapping, or touching along long edge https://www.inaturalist.org/observations/67569071

STERILE FROND FORMS
(1) LENGTH
a. Miniature: plants fertile when small, remain small in old age https://www.inaturalist.org/observations/66415414
b. Short https://www.inaturalist.org/observations/66923628
c. Usual frond length https://www.inaturalist.org/observations/67855528
d. Long, larger plants https://www.inaturalist.org/observations/67924419 https://www.inaturalist.org/observations/67855428
(2) DISPLAY
a. Various, upright & lateral https://www.inaturalist.org/observations/67855528
b. Upright https://www.inaturalist.org/observations/67855364
c. Lateral https://www.inaturalist.org/observations/67855428
(3) BRANCHING
a. Unbranched, usual condition https://www.inaturalist.org/observations/67872751
b. Branched near apex of frond https://www.inaturalist.org/observations/67634975
c. Branched at base of frond https://www.inaturalist.org/observations/68123292

FERTILE FROND FORMS
(1) Combined with sterile frond
a. Fertile portion of frond constricted in comparison to the infertile leaflets of the same frond; fertile portion of frond restricted to the top of the frond; fertile portion of frond shorter than the sterile portion https://www.inaturalist.org/observations/67857342
b. Fertile portion of frond gradually blends into the lower infertile portion of frond; fertile portion of frond equals or somewhat exceeds length of sterile portion https://www.inaturalist.org/observations/67675090
(2) Separate fertile frond https://www.inaturalist.org/observations/67673670

ABERRANT FORMS CAUSED BY PHYSICAL DAMAGE
1) To the crown of the fern https://www.inaturalist.org/observations/68503851
2) To a frond during its growth phase https://www.inaturalist.org/observations/68426233

Anotado por mjpapay mjpapay, enero 13, miércoles 00:57