FNA: Polypodium glycyrrhiza vs. Polypodium

Phenology

Sporulating late fall–spring.

Habitat

Cliffs and rocky slopes along coasts, often epiphytic, on a variety of substrates

Elevation

0–700 m. (0–2300 ft.)

Distribution

AK; CA; ID; OR; WA; BC; YT; Asia in Kamchatka in the former Soviet republics

[WildflowerSearch map]

[BONAP county map]

Worldwide

[BONAP county map]

Discussion

Polypodium glycyrrhiza hybridizes with P. calirhiza and with P. hesperium to produce sterile triploids with misshapen spores. Polypodium glycyrrhiza was involved in the origin of both of these allotetraploid species, and some individuals can be difficult to identify. Free versus anastomosing venation distinguishes this species from P. calirhiza; the presence of adaxial hairs on the rachis separates it from P. hesperium. An additional character for distinguishing these taxa is spore length, which is less than 58 µm in diploid P. glycyrrhiza and more than 58 µm in the two tetraploid species. Reports of P. glycyrrhiza occurring in Arizona (T. Reeves 1981; D. B. Lellinger 1985) are based on misidentified specimens.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Some species traditionally included in Polypodium are treated here in other genera, for example, Pleopeltis and Pecluma.

Except for the tropical species Polypodium triseriale, North American Polypodium is a complex assemblage of interactive species. The North American species have ties to European taxa (e.g., P. vulgare sensu stricto, which probably originated by allopolyploidy between P. glycyrrhiza and P. sibiricum) but are quite distinct from them. Morphologic comparisons and continuing biochemical and molecular studies indicate that two groups of diploid species occur within the North American P. vulgare complex. One group includes P. glycyrrhiza and P. californicum; the second, P. amorphum, P. appalachianum, and P. sibiricum. Allopolyploid species have originated following hybridizations within a species group (i.e., P. calirhiza from P. glycyrrhiza × californicum, P. saximontanum from P. amorphum × sibiricum, and P. virginianum from P. appalachianum × sibiricum) as well as between members of the two groups (i.e., P. hesperium from P. amorphum × glycyrrhiza). These reticulate relationships are summarized in the reticulogram. We consider P. scouleri to be peripheral to the "core" diploids even though hybrids have been reported.

We have not included the European Polypodium cambricum Linnaeus [P. australe Fée], reported from San Clemente Island, California (R. M. Lloyd and J. E. Hohn 1969), in the North American flora because, since the single, original collection, efforts to relocate specimens in nature have failed (R. M. Lloyd et al. 1992).

Because taste is a characteristic used in the descriptions, the reader is cautioned to taste clean rhizomes from uncontaminated soils.

Species ca. 100 (11 in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key

1. Leaves 1-pinnate at base; venation anastomosing, forming 2–3 or more rows of areoles on both sides of costae; sori in 2–3 rows on both sides of costae.	P. triseriale
1. Leaves pinnatifid; venation free or, if anastomosing, only occasionally forming more than 1 row of areoles on both sides of costae; sori in 1 row on both sides of costae.	→ 2
2. Mature blades leathery, stiff; sori more than 3 mm diam.; venation always anastomosing, forming 1 row of areoles; leaf segments more than 12 mm wide.	P. scouleri
2. Mature blades herbaceous to leathery, rarely stiff; sori less than 3 mm diam.; venation free to anastomosing, occasionally forming 1 or more rows of areoles; leaf segments usually less than 12 mm wide.	→ 3
3. Rachises and segment midribs puberulent adaxially; segment margins usually serrate.	→ 4
3. Rachises and segment midribs essentially glabrous adaxially; segment margins entire or crenulate, but rarely serrate.	→ 6
4. Scales on abaxial surface of rachises linear and hairlike, less than 3 cells wide; venation entirely free; stems intensely sweet, licorice-flavored.	P. glycyrrhiza
4. Scales on abaxial surface of rachises narrowly lanceolate to ovate, usually more than 3 cells wide; venation often anastomosing; stems acrid, sweet, or bland, but not licorice-flavored.	→ 5
5. Blade widest near base, proximal 1–3 pinnae equal to or longer than more distal pinnae; several areoles present on leaf segments; spores usually less than 58 µm; coastal California s of Humboldt County.	P. californicum
5. Blade widest above base, proximal 1–3 pinnae shorter than more distal pinnae; areoles often absent from many leaf segments; spores usually more than 58 µm; California n of San Luis Obispo County to s Oregon.	P. calirhiza
6. Sporangiasters absent (although occasional misshapen sporangia may be present); stem scales usually entire and symmetric; scales on abaxial surface of rachis linear-lanceolate, less than 6 cells wide; immature sori oval.	P. hesperium
6. Sporangiasters (with bulbous heads with or without glandular hairs) present; stem scales usually coarsely toothed and contorted distally; scales on abaxial surface of rachis lanceolate-ovate, more than 6 cells wide; immature sori circular.	→ 7
7. Sporangiasters bearing glandular hairs more than 40 per sorus; stem scales golden brown, nearly concolored; blades typically elongate-deltate, widest at or near base; tips of leaf segments acute to narrowly rounded.	P. appalachianum
7. Sporangiasters (with or without glandular hairs) less common, fewer than 40 per sorus; at least a portion of each stem scale dark brown, often distinctly bicolored; blades typically oblong, widest near middle; tips of leaf segments rounded to obtuse.	→ 8
8. Sporangiasters predominantly without glandular hairs; spores usually less than 52 µm; stem scales dark brown throughout or obscurely bicolored with lighter margins.	P. sibiricum
8. Sporangiasters mostly bearing glandular hairs; spores usually more than 52 µm; some stem scales light brown or prominently bicolored.	→ 9
9. Leaf blades more than 3.5 cm wide; e North America.	P. virginianum
9. Leaf blades less than 3.5 cm wide; w North America.	→ 10
10. Sporangiasters consistently bearing glandular hairs; spores rugose with small surface projections less than 3 µm tall; Cascade Ranges.	P. amorphum
10. Sporangiasters bearing a few glandular hairs or occasionally lacking glands; spores with large tubercles, usually more than 3 µm tall; Rocky Mountains.	P. saximontanum