182 Mr. D. Don's Descriptions of new Genera and Species 



Trachodes. 



Involucrum imbricatum. Receptaculum laeve. Achenia subfusi- 

 formia, transversa rugosissima. Pappus sessilis ; radiis basi 

 solutis. 



Involucrum multiplici ordine poly phy Hum, imbricatum, cylin- 

 draceum, tubulatum : squamis exteriorihus ovatis, obtusis, 

 margine scariosis ; intimis 8, elongatis, lineari-ligulatis, con- 

 niventibus. Beceptaculum\ddve. Flosculi indefimti C^O — 24): 

 ligulis 5-dentatis, 6-nerviis. Anthem crista ovat^ acuta ! 

 membranace^ coronatae, basi bidentatae. Stigmata semi- 

 cylindrica, obtusa, cum apice styli papilloso-hispidula ! 

 Achenia subfusiformia, tetragona, apice attenuate acut^ 

 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 pariim dissimilibus. 

 Herba biennis, e viridi ccerulescens. Caulis bipedalis, erectus, ri- 

 gidus, paniculatim ramosus, teres, aculeis minutissimis scaber, 

 basin versus purpureo-maculatus, vix calamum scriptorium 

 crassitie adcequans. Folia radicalia vix spithamaa, subsessilia, 

 spathulata, sinuato-runcinata, mucronata, margine copios^ 

 spinuloso-denticulata, pollicem v. sesquipollicem lata ; caulina 

 amplexicaulia, altius lobata : lobis triangulari-ovatis, acumi- 

 natis. Flores citrini? pedicellati, Lactucae virosae iis vix 

 majores. Pedicelli squamis ovatis margine scariosis muniti. 

 Pappus niveus. Nomen ad plantae asperitatem refert, 

 Tpa)(a>Sr)s, scabrosus, 



1. T. paniculatus. 



Sonchus paniculatus. Herb. S. et M. 

 In Mexico Sesse et Mocinno. c? . 



In 



