182 Mr. D. Don’s Descriptions of new Genera and Species 
TRACHODES. 
Involucrum imbricatum. Receptaculum leve. Achenia subfusi- 
formia, transverse rugosissima. Pappus sessilis ; radiis basi 
solutis. 
Involucrum multiplici ordine polyphyllum, imbricatum, cylin- 
draceum, tubulatum: squamis exterioribus ovatis, obtusis, 
margine scariosis ; intimis 8, elongatis, lineari-ligulatis, con- 
niventibus. Receptaculum leve. Flosculi indefiniti (20—24) : 
ligulis 5-dentatis, 6-nerviis. Anthere cristà ovata acuta! 
membranaceá coronatz, basi bidentate. Stigmata semi- 
cylindrica, obtusa, cum apice styli papilloso-hispidula ! 
Achenia subfusiformia, tetragona, apice attenuato acute 
quadrangulo, angulis prominulis, costisque solitariis v. binis 
insterstinctis, rugis transversis elevatis scabra. Pappus ses- 
silis, capillaceus, mollissimus, fugax : radiis triplici ordine 
digestis, basi solutis ; intimis crassitie parüm dissimilibus. 
Herba biennis, e viridi cerulescens. Caulis bipedalis, erectus, ri- 
gidus, paniculatim ramosus, teres, aculeis minutissimis scaber, : 
basin versus purpureo-maculatus, vix calamum scriptorium 3 
crassitie adequans. Folia radicalia viv spithamea, subsessilia, | 
spathulata, JURO Cunpigatd, mucronata, margine copiose 
ES nticu. pol licem v. sesquipollicem lata ; caulina 
= amplecicaulia, allita lobata : lobis triangulari-ovatis, acumi- 
natis. Flores citrini? pedicellati, Lactuce virose iis vix 
majores. Pedicelli squamis ovatis margine scariosis muniti. 
Pappus niveus. Nomen ad plantæ asperitatem refert, 
Segen scabrosus. 
TNI 
T —. Herb. S. et M. 
In Mexico — a s Mocsano. c. 
