354 MR. J. MIERS ON THE HIPPOCRATEACEA OF SOUTH AMERICA. 
flowers in this group are double the size of those of Hippocratea: in the latter genus 
the petals are oblong, broader at their base, where they touch one another; they are 
fleshy, with entire hairy margins, tomentous outside, and invariably furnished on the 
inside below the apex with a thick tuft of reddish hairs—a constant character, found only 
in that genus, by which alone it is distinguishable from all others; in Prionostemma, on 
the other hand, the petals are much larger, broadly orbicular, suddenly contracted at 
their base into a long narrow claw, are always glabrous on their inner face, as well as 
externally upon their broadly membranaceous margins, which are deeply pectinated 
as in Anthodon and broadly overlap one another in their imbricated æstivation. In 
Hippocratea the disk is tall, conical, fleshy, tomentellous outside, and furnished with 
a thickly tomentous ring around its truncated summit; in Prionostemma it is more de- 
pressed and more pulvinated around the central cavity in which the ovary is seated, 
and is expanded at its base into a broad glabrous thin margin, with its edge turned 
up like the border of a saucer, concealing the claws of the petals, which are attached 
beneath it. In Hippocratea the anthers are prolonged at their back by a cuneiform 
connective, which is seated on the apex of the recurving filament. Prionostemma has 
similar anthers, but without any intervening connective, and they are extrorsely attached 
at their back by a small point below the apex of the filament: the ovary is more de- 
pressed than in Hippocratea, the axis becoming equally atrophied ; and the three ascending 
growing lobes are furnished on their external angle with long white hairs, which are con- 
tinued along the angles of the trigonous long subulate style, the latter being terminated 
by three short, white, erect, ciliated, connivent stigmata—in all which respects the two 
genera differ. The fruit consists of three bilocular capsules, like those of Hippocratea, 
but they are more convex: the seeds are winged in a similar manner, but the nucular 
apex, when fully matured, is more swollen, and contains an exalbuminous embryo, of an 
oblong, rounded or subcompressed form, consisting of two fleshy convex cotyledons, 
which are conferruminated together into a solid mass, with a small basal radicle ; this 
structure of the embryo is shown in its transverse section, where the line of union of 
the agglutinated cotyledons is distinetly seen ; imbedded in this cotyledonary mass, nu- 
merous oil-cells are seen arranged in several longitudinal series, near its periphery, of 
which we find no trace in Hippocratea. 
The plants are arborescent, with pendent or subscansile branches, which are often sub- 
alternate (another peculiarity); their leaves are oval or oblong, coriaceous, rigid, with 
entire margins and very prominent nervures, and are covered on both sides with raised 
asperities, very sensible to the touch—all distinctive characters. 
The generic name, derived from zpiwy, serra, oréuua, corona, is given to it because of the 
floral eoronet of five expanded pectinated petals and sepals in the flower. 
PRIONOSTEMMA, gen. nov. 
Hippocratee sp. auctorum. 
Sepala 5, subrotundata, crassiuscula, glabra, vel in medio utrinque pilosula, margine tenui pectinato- 
dentata. Petala 5, alterna, triplo longiora, quorum 2 interiora paulo minora, late orbicularia, imo 
subito et breviter unguiculata, sub limbum disci inserta, in medio carnosula et utrinque sparse pilo- 
í 
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