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Show The Hijlory ()f P L A N T S. M 0 s s E s. Clafs the Third. Genus the Seco1td. PLATYSMA. PLATysMA is a genus of Mo!res, confifiing of a ~rm, tou~h, and flexile mat .. ter, formed into ramifications, ~hich are flat and thm, and, m fame degree, re-femble, in their divifions, the fea fuct. . . . Thefe Mo.lfes have the fame appearance of fruchficatt~ns with t,?e ufnere; they h~ve roundifl1 fcutellre growing bn the edges, or furfa~es, of the1r leaves, m many p~r~s, wh~ch cwidently ferve to the propagation of the fpec1eS, though the exaCt manner m whtch that is performed is not yet difcover<~d. . The later botanical writers have made all thefe plants fpec1es .of that enormous ge-nus lichenoides, or, according to Linnreus, lichen, which takes m a yet grea~er !~umber ; but, though it mull: be allowed that the fruttific~tio~ appears much a.hke m all thefe it is ra!h to determine that it is really perfettly ahke m all, from the l1ttle we at prefe~t know of it; and it is impratticable to e~abli~ generical charatters on the parts of fruCtification in plants in which we are fo lmle mformed what thofe parts truly are. Micheli led Linnreus into this; but not even the reverence d~e. to . two fu ch names as thefe ought to plead againfi: innovat~on, in a. cafe v:rh~re the ?1ihntt1~n off~ many hun .. dred plants as are included under thxs term l1chen IS 1mpraC:bcable without H. 1 • Platyfma reticulatum marginibus fcutelliferis. ®ilk JLung,S. The reticulated P latyfina, with the flute/lee on the edges. This is the Iargell: of all the plants .of this genus. It grows t.o the tree~ on wl~i~h it is found by a firm, and fomewhat thtck, woody bafe; from this there a11fe fometunes one fometimes more difiinct plants. Each plant Is, near the bafe, a ? road and flat fubftance, of a rough furface, and full of vein~ and ri~ngs: It expands 111 b~eadth. for half an inch, an inch, or more, and then begms to diVancate, or feparate ttfdf m~o fegments. The whole plant is fi·equent\y eight or ten inches long, and fix or m or~ m diameter. The feveral fegments, where they are feparate, are ufually about hal~ ali inch broad, but they frequently .coale(ce, and form a conti.nued. fubfian:e, of an ~~~h or two in breadth; and, what IS more fingular, thofe ram1fic~t1ons, wh1ch. go off brfl: from the main plant, ofren unite themf~lves to it again at .their ends; a thwg no_t ur~common in the vegetation of the fubmanne plants, but wl~Ich we do not meet wi.th 1.n any other, except this and fame other of the Moifes of th~s claf~. The feveral divancations are variouO.y divided into fegments, and ufually term~nate 111 a forked end . The whole plant is of the thicknefs of a firong parchment, and 1s alm~fi: as tough a~ leather. It's colour is a pale browni!h yellow. The furface of the whole IS extremely Irregular. There are prominent veins running all over it in an irregularly re ticulated form ; between thefe there are a multitude of depreffions, which form as many protuberances on the under fide. Thefe prominent parts are paler than the refl: of the u.nder fid~, which is fometimes only a little darker than the upper, and fometimes. b~aclufh, ~nd ~s fomewhat downy, and fends out, at certain difiances, a number of ctrn, by wluch rt fixes itfelf down to the tree, or to the Mo.lfes on it's fur face. On the edges of the fegments, and in the feveral parts near them, grow a great number of fcutellcc; they are not very large, but very hard, folid, of a reddifh brown on the upper fide, and pal~r underneath. On the edges of the fegments alfo, and in fomc places along the prOtmnent ribs of the plant, near the extremities, there appear rows of little protuberances, of a grey colour, and formed of congeries of a dull:y matter. It is highly probable that thefe have fome {hare in the fruttification, but what that is, or whether they belong to the male or female parts, is not eafy to be determined : Micheli. makes them the female parts, but, we are afraid, without fu fli cient foundation. Lrefelius and R uppius have defcribed the farinaceous and peltiferous plants of this fpecies as two different fpecies. Nor is this, indeed, the only infiance of more than one plant being made out of this. It varies extremely in it's manner of growth: it's young leaves are fmall, and particularly divaricated3 fo as to feem. different plants. M.icheli The Hi.flory of P L A N T S. 8g Micheli has figured thefe, and Bohart mentions a variety of it, with fegments three times as broad as they ufually are; the fegments are fometimes alfo f'Gmnd narrower, and undulated at the edges, in which cafe the whole furface of the leaf is generally fmoother, and, fometimes, it grows very {hort, and divaricated into a great number of divifions at the extremities. It is a native of England, but is more common in other parts of Europe, where there are th icker forefi:s. I have met with it, however, very fine in Charlton-foreft in Su.lfex. It grows to the oak, beach, and other trees. It's fcutellre appear in winter. T he botanical writers, in general, have mentioned this fpecies; it is known in the :lhops, under the name of Pulmonaria ; and the common people with us call it, Tree longwort. Pulmonaria, and Mufcus pulmona:ius, ~re the names alfo that. it ~ands under in more of the authors. Aldrovand calls tt, Lichen arboreus; and Dillemus make it a Lichenoides. All the authors who have figured it, however, except Micheli, have omitted the fcutellre, which is wonderful, for they are frequent enough on it. 2. Platyfma molle angu.flius. The Joft and narrow P latyfma. This is one of the mofi common Mo!res we meet with; hot oniy trees of all kinds are frequently, in a manner, covered with it; but old boards, fuch as pales, gates, and the like, afford it in the fame abundance. Sometimes one, fometimes more plants, arife from the filme root : It is fingle at the bafe, and ofthe fixth of an inch, or thereabout, in breadth ; but it foon divides into a multitude of ramifications, which fubdivide again into others, and finally terminate in forked extremities. It grows to an inch and half, or two inches, in length, and it's tufts oflen are nearly as much in diameter. It's furface is tolerably fmooth; it's colour a pale grey, or bright a01 colour ; and it is remarkably foft to the touch. It is tough and th in, and is of an infipid tafl:e, but with fomething of a!lringency in it : it is often full of hollows on the upper furface, and always fomewhat downy beneath. I t's divarications have been thought by fame to refemble thofe of a flag's horns; they are ofren dichotomous, as in many of the fea fucus's; fometimes trichotomous, fametimes perfec:tly irregular. When this plant produces it's fcutellre, it's fegments are ufually narrower ; the fcutell<r! grow at the extremities and along the edges. The other plants have, at their edges alfo, and on the prominent veins that furround the little cavi ties on the furface, a kiud of farinaceous globules, which evidently alfo ferve for the of11ce of fruttific:ttion. Whether thefe are the male or female parts, is not known; but they feem in this fpecies to grow on dillintl: plants from the male, though in the former on the fame. This common fpecies of Platyfma differs fo greatly from itfelf, under it's various circumflances of growth and fruttification, that we could point out no lefs than thirteen fe veral var ieties of it, which are defcribed by authors, as diflintt fpecies of Lichenoides. While young, it's fegments are few, and are crifl:ated ; afterwards it varies fcve ral times, before it arrives at it's fu ll growth : when young, it has few depreOions; when full grown, it is ufually full of them. The fegments are fometimes very broad, fometimes very"narrow, often fimbriated at the edges or extremities: fometimes the ramificat ions are few, fometimcs they are extreamly numerous. Almoft all the botanical writers have defcribcd this under the names of Lichen arborum, and Lichenoides arborum . Imperatus calls it, Foglio diramato. Others, Ceratites mufcus arboreus, and Bronchialis. It is fingular that Micheli never faw more than one plant of this with the fcutellre, though common enough in Italy. With us the fcutelh:c are very frequent on it. 3· Platyfina finuofum Jcutellis ovato-rotundis. Sinuous P latyfina, with flat, rounded Jcutellce. This is the fpecies commonly called grey, ground liverwort, and famous for the cure of the bite of a mad dog. It is a large and fpreading plant for one of this genus. It grows fometimes fingle, fometimes feveral leaves rife fi·om the fame bafe. They are three or four inches long, and are two inches, or more, in breadth, when difiintt ; but they often grow together in fuch a manner, as to make a fur face of four or five inches broad. The leaf, in it's true f11ape, is fomewhat fmall at the bafc, and gradu- Aa ill |