T R IC H O M A N E S . Lin n .
D id y m o g lo s s u m . Desv. H y m e n o s t a c h y s et F e e a . Bory.
Sori marginales. Sporangia sessilia (annulo completo transverso) receptáculo com-
' muni filiform! producto inserta, in tra indusium cyatliiformem monophylliim tex tu ra
frondis.—Filiculæ plerumque repentes, caudice seu rhizomate filifo rm i, rarius coes-
pitosce, proecipue tropicæ. Frondes simplices, varie divisæ vel decompositæ, membranaceæ,
pellucidæ, costatæ, pulcherrime reticulalæ, atro-virides, non raro siccitate
nigrescentes ; fertiles quandoque difformes spicaloe. Pubes e pilis simplicibus aut
stellatis. Indusium “ e bullata compagine lobulorum binorum lateralium confluentium
ortum." (M a rt.) Receptaculum e vena elongata frondium basi sporangiferum.
Sporulæ lobatæ quasi e tribus seu quatuor formatoe.
Trichomanes alatum. Sw.— non Hook, in Fl. Fond. ( T a b . X X X I .) Hook, et Grev.
le . Fil. tab. X I.
The present and the following Genus {Hymenophyllum') are excluded from the true
Ferns in Presl's able work, and Endlicher had previously constituted of them the Order
HymenophyllecB, chiefly distinguished by the complete transverse ring to the sporangia, the
filiform exserted receptacle, and the delicate texture of the frond ; but we prefer Brown’s
arrangement in making them part of Polypodiaceoe, ranking near Davallia and Loxsoma.
Mr J . Smith well observes—“ In Davallia, the pedicels of the sporangia are free, and
rise vertically from the apex of the vein; in Loxsoma (see Tab. 15), they are united
(but not quite their whole length), and form a columnar receptacle, the sporangia being
placed one above another, and inclining a little outwards, which, according to my view,
accounts for the obliquity of the ring in that Genus but in Hymenophyllum and Trichomanes,
the sporangia are sessile around the columnar receptacle in an imbricated manner,
the upper edge inclining a little outwards, their attachment being slightly excentric, with
the ring placed vertically (as regards the receptacle) on the exterior side of the base or
point of attachment ; and this is quite analogous to the flattened sporangia of the compact
sori in Alsophila and Cyathea, and other Genera which have sessile sporangia on an elevated
receptacle, upon which character Presl has formed a very unnatural and untenable Sub-Order,
which he calls “ Helicogyralæ.”
The species of the present Genus are very numerous and highly beautiful ; one species,
and one alone (the T. brevisetum), is familiar tn the British botanist as an inhabitant of
moist rocks in the vicinity of cascades at Powerscourt, near Dublin, and about the Lakes
of Killarney, Ireland.
F ig . 1. 2. Under and upper side of a portion of a frond ; magn. 5 diam.—/ 3. A sorus, under
side, and f . 4. do. lower side ; m. 15 diam.—/ 5. Under surface of the same, with part of the indusium
removed ; m. 15 diam.—/ . 6. Base of the receptacle, with sporangia ; m. 25 diam.—/ 7. do.,
with the sporangia removed in front ; m. 25 d i am .- / . 8. Small portion of the indusium, and f . 9. do.
of the frond ; m. 100 diam.—/ 10. Sporangia in different stages ; m. 100 diam.—/ U . Sporules ; m.
200 diam.
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