Volume 35 Number 2 & 3 April-July 2008 Editors: Joan Nester-Hudson and David Schwartz Pyrrosia by Tom Stuart [email protected] Pyrrosia is an Old World genus of polypods, mainly tropical, mainly epiphytic, and mainly with simple, entire fronds. Each of these characteristics have exceptions. Peter Hovenkamp's 1986 A Monograph of the Fern Genus Pyrrosia reduced the number of species from over a hundred to fifty-one. It also subsumed several genera, among them Cyclophorus, Drymoglossum, and some Niphobolus species into Pyrrosia. He brought coherence to a chaotic assemblage.* Pyrrosia is distributed from the West Coast of Africa to Madagascar, to India, across the Himalayas, northeast to Russia, southeast into Malaysia, Australia, and on into the Pacific as far east as the Pitcairns. Henderson Island of the Pitcairns is almost directly south, far, far south of Juneau, and is the easternmost outpost. Pyrrosia serpens is epiphytic on Pisonia grandis–a tree in the four o'clock family, dominant on the island. This coral mount is inhabited by nine ferns, 54 seed plants and occasional typhoons. Among the other ferns are the Bird's Nest, Asplenium nidus, epilithic on limestone outcrops or again as an epiphyte on Pisonia, the Whisk Fern, Psilotum nudum–leafless and rootless as ever, but strictly terrestrial here, oddly never on trees as elsewhere, the Giant Hare's-foot Fern, Davallia solida–again epiphytic in Pisonia forests–and two Nephrolepis species–both rock-dwellers. At the western end of the Pyrrosia range, P. schimperiana has an African distribution centered on the equator and encompassing half of the continent. Pyrrosia schimperiana is principally an epiphyte, but also found on exposed or lightly shaded rock outcrops. In between P. schimperiana in Guinea and Pyrrosia serpens on Henderson–15,000 miles–are 49 other epiphytic or epilithic Felt Ferns. Just for a moment, look at the Old World map and the distribution of species on the next page. Would you like to hazard a guess as to the center of distribution of Pyrrosia? Would you expect perhaps Malesia (biogeographically the Malaysian peninsula, Indonesia, New Guinea and the Philippines) or Southeast Asia or would you favor the Himalayas? Hold onto that thought. * Another view was expressed by Shing and Iwatsuki (1997). Though not dealing with the entire genus, the treatment clearly leads to a larger number of species. This circumscription appears to dominate in the currently developing Flora of China; see volume 3 at http://flora.huh.harvard.edu/china/. Fiddlehead Forum u April-July 2008 u Page 9 Numbers reflect the species count within the area. 1-3 counts not shown. What makes a Pyrrosia a Pyrrosia? Among other characteristics, simple leaves. They can be quite varied in outline; here is P. abbreviata of Sumatra and Java. Besides many frond forms we see a typical rhizome, this one long-creeping. Other species are short-creeping, branching, and congested. The long-creepers like this are slow to form good horticultural specimens. All Pyrrosia have hard, dense, often brittle rhizomes. These have a high composition of sclerenchyma cells. Sclerenchyma cells are dead at maturity, composed solely of thick cell walls; tree ferns have a lot of sclerenchyma, too. The presence of sclerenchyma is sparse in other polypods, except for Platycerium. That's another story. The presence or absence of schlerenchymatous (strengthening) tissue and patterns shown by these cells are of diagnostic help for taxonomists. The rhizome (lower left) is always covered with scales (example upper left). These scales differ greatly from species to species as to attachment, size, shape, and margins. You can use these diagnostically with a hand lens and a description. Though scales on rhizomes are not accessible on many ferns, since they are subterranean, Pyrrosia rhizomes are mostly just touching or barely immersed in the substrate. Of course all polypods have naked sori, and Pyrrosia is no exception. Most species also have round sori as with the majority of polypods; sometimes they are elongated or multiple sori are fused into (Hovenkamp, Peter. 1986) long chains called coenosori. A particularly distinctive characteristic of Pyrrosia is the presence of stellate hairs, shown schematically here. All Pyrrosia spp. have these hairs, sometimes two kinds in two layers. Most often they are sparse on the upper surface and dense on the lower surface. The dense mat gives the genus its common name, felt fern. You can see these hairs with a hand lens, though sometimes they are only evident on young fronds. They vary from one species to another in color–white, translucent, tan, or red– or form–needle-like or boat-shaped or woolly rays. (Hovenkamp, Peter. 1986) Platycerium also have these hairs. Yes, another story. Page 10 u Fiddlehead Forum u April-July 2008 In addition, some Pyrrosia have excretions of calcium on the upper surface. AFS OFFICERS These are visible as white dots called hydathodes. Hydathodes are found PRESIDENT: David Conant, Lyndon State College, on other ferns, but not commonly, so it can be a good indicator character. PO Box 919, Lyndonville, VT 05851-0919 David. To round out the indument account, a few other characters are useful [email protected] PRESIDENT-ELECT: Warren D. Hauk, 517 Samson for their exclusionary value: venation: always netted, but quite varied in Talbot Hall of Biological Sciences, Department of details and often obscured; phyllopodia: (stump-like extensions above the Biology, Denison University, Granville, OH 43023 rhizome to which the fronds are jointed) are always present–common in [email protected] SECRETARY: W. Carl Taylor, Division of the Polypodiaceae–and are covered with the same scales as the rhizome. Environmental Biology, National Science Characters of little value in establishing the genus include the stipe: it Foundation, 4201 Wilson Boulevard, Arlington, VA 22230 [email protected] varies from none to longer than the lamina; frond dimorphism: Pyrrosia TREASURER: James D. Caponetti, Division of range from monomorphic to strongly dimorphic; paraphyses: (indument Biology, M303 Walters Life Sciences Building, University of Tennessee, 1414 Cumberland Avenue, within the sorus –here always stellate hairs) vary from undifferentiated Knoxville, TN 37996-0830 [email protected] (compared to nearby hairs) to slightly modified to absent. MEMBERSHIP SECRETARY: George Yatskievych, Missouri Botanical Garden, P.O. Box 299, St. Louis, Lastly, the felt. A majority of the species do exhibit a feltiness in one degree MO 63166-0299. [email protected] or another, but there are exceptions. For example, Pyrrosia piloselloides of CURATOR OF BACK ISSUES: James D. Montgom- ery, Ecology III, Inc., 804 Salem Blvd, Berwick, PA southeast Asia, China, Japan, and Sri Lanka is succulent. Though it has 18603-9801. [email protected] sparse stellate hairs on young fronds, the hairs soon fall, and one is left CURATOR OF THE SPORE EXCHANGE: Denia Mandt, 12616 Ibbetson Ave, Downey, CA 90242- with a shiny surface. (As an aside, this fern exhibits Crassulacean Acid 5050. Metabolism just like the jade plant. Looking for a dissertation subject? WEBMASTER: Stephen McDaniel, 1716 Piermont Explain why CAM shows up in some ferns. Or a preliminary question: Ave., Hacienda Heights, CA 91745. webmaster@ amerfernsoc.org did it arise independently?) The felt-like texture has two origins. The OUTREACH COORDINATOR: Tom Stuart, PO Box fine hairs, particularly when they include woolly ones, can support a felt 517, Croton Falls, NY 10519. [email protected] description on their own. However, the laminar surface in most Pyrrosia EDITORS OF AFS PUBLICATIONS species is not two-dimensional but cobbled or pebbled; I think this light- AMERICAN FERN JOURNAL: Jennifer Geiger, scattering surface is contributory to a felt-like appearance. Department of Natural Sciences, Carroll College, Helena, MT 59625. [email protected] Even if you are not a pteridologist, you can distinguish a Pyrrosia because MEMOIRS: David B. Lellinger, 16 Nottingham it has creeping, surface-dwelling, scaly rhizomes, simple fronds jointed to Rd., Brevard, NC 28712-9785. dlellinger@ earthlink.net the rhizome, naked sori, stellate hairs, and sometimes sports hydathodes. FIDDLEHEAD FORUM: Joan Nester-Hudson, Box This combination of characters is unique. 2116, Department of Biological Sciences, Sam Houston State University, Huntsville TX 77341- 2116 ([email protected]) and David Schwartz, Where does Pyrrosia fit into the tree of life? 9715 Chirtsey Way, Bakersfield, CA 93312-5617 ([email protected]) Two methods are commonly used to demonstrate next of kin. The The Editors of FIDDLEHEAD FORUM welcome traditional method compares the morphology of taxa. In Pyrrosia the contributions from members and friends, including miscellaneous notes, and reviews of books on ferns. unusual characteristics are stellate hairs on the fronds and sclerenchyma Articles may be submitted electronically on disk in the rhizomes. Stellate hairs are found scattered in the vascular plants. (PC compatible) or typed (using a simple font like In the flowering world they are occasional in the Brassicaceae and rare Helvetica in a minimum of a 12pt font.) Regular membership in the American Fern Society is elsewhere. Among ferns one finds them in a few Hymenophyllaceae on a calendar-year basis and includes access to field members, and otherwise singularly, for example, in Astrolepis sinuata trips and the spore exchange. Regular members receive Fiddlehead Forum, but not the American and Dicranopteris linearis. There is no genus outside the Polypodiaceae Fern Journal, for $12 (+$3 expedited delivery fee, sporting stellate hairs unanimously. Among the polypods, there are two: except U.S.A., Canada, and Mexico) Individuals interested in regular or journal member ship should Pyrrosia and Platycerium. contact the membership secretary. A massively sclerified rhizome is also a shared character for these two genera. We do not think of the rhizome in Platycerium because it is thoroughly hidden within the base fronds, but cut open a staghorm fern, AFS HOME PAGE and there is a hard, dense rhizome.