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



Trachodes. 



Involucrum imbricatum. Receptaculum laeve. 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\seve. Flosculi indefiniti (20 — 24): 

 ligulis 5-dentatis, 6-nerviis. Anthera crista ovat& acuta! 

 membranacea coronatse, basi bidentatae. Stigmata semi- 

 cylindrica, obtusa, cum apice styli papilloso-hispidula ! 

 Achenia subfusiformia, tetragona, apice attenuate- 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 partim dissimilibus. 



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

 gidus, paniculatlm ramosus, teres, aculeis minutissimis scaber, 

 basin versus purpureo-maculatus, vix calamum scriptorium 

 crassitie adaquans. Folia radicalia vix spithamaa, subsessilia, 

 spathulata, sinuato-runcinata, mucronata, margine copiose 

 spinuloso-denticulata, pollicem v. sesquipolUcem lata ; caulina 

 ample xicaulia, altiiis lobata : lobis triangulari-ovatis, acumi- 

 natis. Flores citrini ? pedicellati, Lactucae virosae Us vix 

 ma j ores. Pedicelli squamis ovatis margine scariosis muniti. 

 Pappus niveus. Nomen ad plantse asperitatem refert, 

 rpaxcoSvs, scabrosus. 



1. T. paniculatus. 



Sonchus paniculatus. Herb. S. et M. 



In Mexico Sesse et Mocinno. cf . 



In 



