223 
Characters of a New Genus of CowPosrrE-EUPATORIACEJE, with re- 
marks on some other Genera of the same Tribe ; by Asa GRAY. 
(Tas. V.) 
DissoTHRIX, nov. gen. 
Capitulum 6—9-forum, homogamum.  Znvolucrum biseriale, floribus 
æquilongum ; squamis laxis mox patentibus, lanceolatis, cuspidato- 
acuminatis, membranaceis, bicostatis, margine scariosis, exterioribus 
brevioribus. Receptaculum parvum, nudum. Corolla anguste cylin- 
drica, apice breviter 5-dentata, dentibus erectis. -dchenium breve, 
acute pentagonum, angulis hispidulis, callo basilari majusculo. Pap- 
pus plurisetosus, biformis, nempe, setis 5 rigidis ad angulos achzenii 
respondentibus corollam superantibus, ceteris (30-40) capillaribus 
brevioribus valde inæquilongis, omnibus sursum hirtello-scaberrimis. 
— Herba Brasiliana annua, glabriuscula; caule erecto striato su- 
perne paniculato laxe polycephalo; foliis membranaceis ovato- 
lanceolatis petiolatis dentatis, inferioribus oppositis, summis alter- 
nis. Corollz apice purpurascentes. 
D. Gardneri (Tab. V.).—Stevia imbricata, Gardner, in Lond. Journ. 
Bot. vol. v. p. 458 (n. 1744 and n. 2211). 
This plant is certainly to be distinguished from Stevia, as well by 
the truly setose pappus, of which even the five stronger rays can 
scarcely be termed aristæ, as by the minutely five-toothed and conni- 
vent limb of the corolla, and the biserial, imbricated, and lax or 
spreading involuere. The thin and smooth scales of the latter are 
strongly two-nerved (in the manner of Brickellia, &c.), and have also 
three very slender intermediate nerves, often scarcely visible except by 
transmitted light. When the achænia fall the scales become reflexed. — 
Judging evidently from the description alone, Gardner compared  - 
this plant with the Stevia calycina of De Candolle, which is doubtless” 
the Eupatorium ? calyculatum, Hook. and Arn. Comp. Bot. Mag. vol. ii. 
p- 242, and therefore the Disynaphia Montevidensis, DC. Prodr. vol. vii, — 
p. 267, to which Dissothrix bears no particular resemblance. 
Respecting Disynaphia, Y may remark that the sete of its pappus 
are rather óarbellulate than scabrous. Also that true congeners 
of D. Montevidensis are, Eupatorium spathulatum, Hook. and Arn. - 
Comp. Bot. Mag. l. c., which is the same as F. halimifolium, DC. - 
(named Z. passerinioides by De Candolle in the Parisian herbarium), - 
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