116 BOTANY OF THE VOYAGE OF THE SULPHUR. 
The plants belonging to the Helianthoid genera with a calyculate pappus are 
very difficult to determine; the distinction between the female rays of Wedelia, 
and the neuter ones of Gymnopsis, Anomostephium, Viguiera, &c., is perhaps not 
constant in some species, nor ever very consonant with habit. Thus the three 
last-mentioned species, published by Hooker and Arnott as Wedelie, appear to me 
to have the ray always neutral or sterile. The achenia of W. strigosa are not yet 
ripe, but seem to refer the plant either to Oyedea or to the section of Viguiera 
with a nearly flat receptacle (very different in habit from the Viguiere with a 
conical receptacle); the W. subflexwosa has the habit as well as the achenium 
and pappus of Gymnopsis rudbeckioides, DC.; and the W. cordata is also very 
near that plant, but the specimens are too young to determine accurately. 
446. Mevantuera deltoidea, Reichb.—DC. Prod. v. 5. p. 545.— Columbia. 
447. Mevantuera oxylepis, DC.? 1. c.—Species colore pallido et rete venarum insignis. 
Variat foliis ovatis integris vel hastato-trilobis—Realejo, Gulf of Fonseca. 
448. Gymnopsis (Aldama) divaricata, sp. n. herbacea, divaricato-ramosa, strigoso-pubescens, 
foliis inferioribus oppositis petiolatis ovatis vel ovato-lanceolatis grosse dentatis basi cuneatis 5- 
nervibus superioribus alternis lanceolatis, involucri squamis uniseriatis ovato-lanceolatis acuminatis 
foliaceis strigosis, receptaculi paleis acheenia glaberrima arcte involventibus obovatis obtusis corru- 
gatis, pappo coroniformi minutissimo.—Gulf of Fonseca. 
Herba 1-1}-pedalis, ramis oppositis vel! dichotomis, divaricato-adscendentibus. Folia inferiora bipollicaria, 
superiora minora, subrugosa, viridia, pilis crebris appressis rigidis preesertim subtus canescentia. Flores fere 
G. uniserialis. Involucri squame subsemipollicares, laxee, latitudine varic. Ligule 5-6, ovario parvo nudo 
tubo elongato, lamina obovata vel oblonga, obtusa, subintegra, lutea. Pales receptaculi virides, villosule, demum 
achenia disci undique involventes et clause, acheenio arcte appresse et subcoheerentes, basi lateraliter affixe, 
nec acuminate nec cucullate. Flores disci longe tubulosi, hirtelli. Styli rami appendice longa hirtella superati. 
Acheenia obovoideo-pyriformia, apice umbonata. Pappus vix conspicuus, e palea brevissime protrudens. 
This species with the G. dentata, DC., G. Schiedeana, DC., and G. uniserialis, 
Hook., to which it is nearly allied, cannot surely be congeners to the Gymnoloma 
of Humb. and Kunth, with which they have been united under the common name 
of Gymnopsis. The remarkable manner in which the fertile achenia of the disk 
are enclosed in the palez of the receptacle, like those of the ray flowers in Melam- 
podium, seems fully to warrant the retaining for them Llave and Lexarsa’s generic 
name, Aldama. 
449. Trruonta angustifolia, Hook. et Arn. Bot. Beech. p. 435. (sp. n.)—Tepic. 
450. Trruonta tagetiflora, Desf.—DC. Prod. v. 5. p- 584.—Realejo, Acapulco. 
451. Hevianruus annuus, Linn.—DC. Prod. v. 5. p. 585.—Isle of Puna, near Guayaquil. 
452. Brnens ¢ereticaulis, DC, Prod. v. 5. p. 598, var. foliorum segmentis minus acuminatis, 
ceeterum speciminibus Mexicanis simillima.— Columbia, 
