POLYTRICHUM SUBROTUNDUM. D\VARF PoLYTRICHUM. 



POLYTRICHUM Linnai. Cryptogamia Muscr. 



Calyptra duplex, interior membranacea, laevis, exterior floccida. 



Rail Syn. Gen. 3. Musci. 



POLYTRICHUM fubrotundum caule fimplici anthera fubrotunda. Hudfon FL Angl. p. 400. 



MNIUM Polytrichoides calyptra villofa. Lin. Syji. Vegetab.f. 796. Sp. PL p. 1576. FL Suecic. p. 385. 



MN1UM calyptra villofa, acaulon, foliis ferratis, capfulis cylindricis ere&is. Halkr. hifi. n. 1837. 



POLYTRICHUM Aloefolium. Scopoli FL CarnioL p. 309. n. 1290. 



POLYTRICHUM nanum, capfulis fubrotundis galeritis, aloes folio non ferrato. The dwarf round- 

 headed Aloe-leaved Polytrichum, Dillen. Mufc. 428./. $$.f. 6. 



POLYTRICHUM nanum capfula cylindrica erecta; furculis fimplicibus, breviffimis, foliis ferrulatis. 

 Weis Plant. Cryptogam, p. 173. 



MUSCUS capillaceus minor, calyptra tomentofa. Vaill. paris. 131. t. 26. f. 15. 



ADIANTUM aureum medium, in ericetis proveniens. Vaill. paris. 429. /. 5$. f. 7. 



MUSCUS coronatus rigidus minor et humilior capitulis villofis brevioribus. Moris, hift. 3.^. 630. /. y.f. 7. 



POLYTRICHUM minus capfulis fubrotundis, calyptra quafi lacera coronatis. C. G. 221. Raii Syn. 

 p. 91. 



RADIX tomentofa. | ROOT woolly. 



CAULIS breviffimus, vix ullus. | STALK very fhort, fcarce any. 



FOLIA brevia, rigida, intus concava, extus convexa, % LEAVES fhort, rigid, hollow within, round with- 



acuta, margine minutimme ferrata, bafi lato | out, fharply pointed, the edge very finely 



membranaceo caulem ample&ente, ficcata in- $ ferrated, embracing the ftalk by a broad mem- 



curvata teretiufcula, fig. 1. branous bafe ; when dried bending inwards, 



I and of a roundifh form, fig. 1 . 



PEDUNCULIfimplices,unciales,rubicundi,fubdiapha- % FOOT-STALKS fimple, an inch high, reddifh, fome* 



ni, flexuofi, fig. 3, demum tortuofi, fig. 21. | what tranfparent, crooked, fig. 3, finally 



I twifted, fig. 2 1 . 



CAPSULE fubrotunda, fig. 4. | CAPSULES roundiih, fig. 4. 



Fig. . 2, Folia per lentem vifa. | Fig. 2, The leaves viewed through a magnifier. 



5, Calyptra exterior magn. nat. $ 5, The exterior Calyptra of its natural fize. 



6, Eadem magn. aud. | 6, The fame magnified. 



7, Eadem inverfa ut Calyptra interior f 7, The fame inverted, that the inner 



appareat. t Calyptra may appear. 



9, 9, Calyptra interior in fitu naturali. | 9, 9, The inner Calyptra in its nat. fituation. 



10, 10, Eadem auda. ¥ 10, 10, The fame enlarged. 



li, Calyptra interior feparata ab exteriore | 11, The inner Calyptra feparated from the 



et feorfim exhibita. $ outer one, and ihewn by itfelf. 



12, Eadem in fitu naturali cum exteriore ? 12, The fame in its natural fituation, con- 



connexa. 



f 



neded with the outer one. 



13, Capfula magn. nat. nuda. ¥ 13, The Capfule of its nat. fize uncovered. 



14, Eadem aud. | 14» Tne fame enlarged. 



15, Eademadmaturitatemmagisaccedens. | 15, The fame approaching more to maturity 



16, Operculum. * 16, The Cover. 

 17, 17, Ciliae. I 17* *7> The Ciliae. 



18, 18, 18, Membrana mucronata in fummo cap- * 18, 18, 18, A pointed Membrane at the fummit 



fuhe cui adneduntur ciliae. | of the Capfule, to which the Cilia; 



* are connected. 



19, 19, Cilige in fedione longitudinali Capfula | 19, 19, The Ciliae mewn in a longitudinal fec- 



exhibitae. I tion of the Capfule.^ 



20, Receptaculum feminis. ¥ 20, The Receptacle to which the feeds 



t are connected. 



ABOUT two years ago, (1776) on examining the ftrudure of the Polytrichum commune, in a very young ftate, 

 I found one of the heads, (Anthera Linn.) after I had diverted it of its woolly Calyptra, covered with a membra- 

 nous mining fubftance, and which 1 had no fooner feen, than I judged it to be a Calyptra, being fo very fimilar 

 to the Calyptra's of fome MofTes I had juft before been examining; and on a more minute^ inveftigation, I 

 found it to be a real Calyptra, not accidental to the plant then under examination, but occurring In_ all thofe 

 which I, at that time, had an opportunity of diffeaing ; and afterwards found to be in the dwarf variety of the 

 fame fpecies, growing on heaths, and in the prefent plant. 



Thofe who mail take the pains of investigating the ftrucl:ure of thefe MofTes, will think it ftrange that a part 

 fo very obvious to the naked eye, mould not have been noticed before; but this is eaflly accounted for. 



No one, when he fits down to examine thefe MofTes, conceives a priori, that they have any more than one Ca- 

 lyptra ; finding that which is peculiar to this Genus, he refts fatisfied, pulls it off, and proceeds to the examination 

 of the remaining parts, not imagining that a membranous Calyptra is clofely conneded by its apex to the woolly 

 one, pulled off with, and covered by it, and fcarce difcovered but by totally inverting it : but that this is a&ually 

 the cafe, any one may fatisfy themfelves in the courfe of this and the fucceeding months, February and March. ^ 



This inner Calyptra differs very little from the Calyptra of other MofTes ; at firft it wholly furrounds the unripe 

 Capfules, as they increafe in fize it fplits at bottom, and finally becomes very fhort. 



I was the more pleafed with this difcovery, as I conceived hopes it would place the genus Polytrichum in a more 

 pleafing and fatisfadory point of view ; and I have accordingly ventured to alter its generic character as above : by 

 this alteration it is brought from the Mniums, among which it is placed by Linnjeus and Haller, and arranged 

 with the Polytrichums of Dillenius, Hudson, Scopoli, and Weis, to which its habit alone certainly entitles it, 

 was it not found to accord with the Polytrichum in the efTential character now difcovered. 



Why nature mould have been thus careful in covering this genus of plants with a warm additional coat, while many 

 of the other MofTes, at the fame time of the year, are thinly clad with a fingle membranous veil, does not appear. 

 In the ftrudureofthe two Calyptra's, there is amoft eflential difference ; the outer one being a woolly fubftance clofely 

 matted together, without any conneding membranous fubftance ; the inner one confifting wholly of membrane. 



The plant here figured, is the Polytrichum capfulis fubrotundis of Dillenius, and of which that, with the capitulis 

 cblongis, feems to be only a variety growing in warmer and lefs expofed fituation s. 



It is by no means an uncommon Mofs on our heaths, and expofed hilly and fandy places about town. It 

 throws out its ftalks in November and December^ and ripens its Capfules in January and February. 



