VARIATION IN POLYSTICHUM ACROSTICHOIDES

NOTE: This post replaces 10 January 2021, whose errors were corrected. Also, a few links were added or replaced. [Most Recent Update: 16 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, points toward the stem tip.
a. Short - wider than tall https://www.inaturalist.org/observations/67591938
b. Usual - about as tall as wide
c. Tall - taller than wide https://www.inaturalist.org/observations/67538230
d. Separate - as a lobe, usually restricted to lower (basal) leaflets https://www.inaturalist.org/observations/67592332
(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

Publicado por mjpapay mjpapay, 13 de janeiro de 2021, 12:57 MANHÃ