Pyrrosias, with their unfernlike appearances, come to our temperate gardens, our contrasting subtropical comforts, and the luxury of greenhouses as felt ferns. The common name describes the coating of hairy silver stars that decorate the unfurling fronds. These will mature to a soft, felt-like, rusty blanket that persists on the fronds' undersides and protects the indusia-free developing spores.
Pyrrosia is a genus with short- to long-creeping rhizomes, with those of many species slender and wiry, while others are thick and stubby, all with matching stipes. Stipes are stiff and strong, often up to or more than half the length of the frond. Sentinels of round, elliptical or vertical tongues of simple, undivided, usually upright blades may be densely packed or widely separated as the rhizome creeps forward. The blades are clearly split by a prominent and succulent midrib, which in some species branches into linear subdivisions reaching to the margin of the frond. Netted veins, which may in turn enclose a singular veinlet (tail), are characteristic and are found between the linear veins or, when these are absent, independ ently. The vascular bundles are, well, presumably there given some imagination. My microscopic examination of stipe cross-sections, sacrificed from four different species, shows mostly pith. (Botanically speaking, the vascular bundles have to be present, but they are certainly not readily visible.)
As a rare occurrence, some species have what are technically known as hydathodes. These are specialized structures that secrete water, usually from the tip of a gland, and deposit a minute, telltale white speck on the upper frond surface. For identification purposes, and Botany 450 exams, look for crystals that give the frond the appearance of having been very lightly sprinkled with salt.
Sori without indusia are distributed on or between veins and often camouflaged under the protection of the stellate canopy. Spores are yellow. Most do not mature during the traditional summer harvest time, but cling to the parent until late winter. In the Pacific Northwest, droppings of yellow-gold, which could easily be mistaken for an erratic distribution of some mysterious alien pollen, are produced in late winter. Propagation is easily accomplished by division and not so promptly by spores. Spores of some species germinate readily and develop at a leisurely pace. Others germinate reluctantly and develop at an even more leisurely pace. Spores are best sown on sandy compost and the resulting plants, if any, need good drainage and partial shade.
With their distinctive, non-traditional, foliar structure these are plants to be featured in special sites. Give them a
coarse mix or whatever good-draining soil is at hand. I have never given mine any fertilizer. They are not demanding and, even when benign neglect leaves them in a frightening state of wilt and despair, will respond to a good drink, eagerly looking brand new.
There are from 50 to more than 70 species worldwide, depending on your botanical reference, with a native range spreading across a broad spectrum of homelands including Japan, China, the Indian subcontinent and the Himalayas, New Zealand, and Australia as well as Africa and islands of the South Seas. Explicit in this distribution description is the exclusion of North and South America. The genus name is derived from the Greek pyrros, meaning flame or fire in reference to the persistent, brilliant rusty hairs that decorate the fronds' undersides.
Historically, herbal remedies and medicinal properties associated with this genus date back some 5000 years and are remarkable and extensive in Asian cultures. They included multipurpose cures for many ailments. Compounds, especially from Pyrrosia lingua and P. sheareri, are still offered in contemporary Chinese medicine as remedies for assorted ills from bronchial infections and asthma to serious kidney and urinary tract disorders.
Away from the medicine chest, when used for garden enrichment, these are notable and distinguished ferns that are guaranteed to please the grower and surprise the uninitiated with their unusual silhouettes.
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