of the Class Compositce. 181 



In Mexico. Sesse et Mocinno.ii • 



Herba perennis, caespitosa, glabra. Radix fusiformis. Caules 

 plures ex eadem radice, erecti, spithamsei, filiformes, uni- 

 flori, lreves, folio unico, lanceolato, integerrimo, sessili ad 

 medium v. paulo infra, inde squamis aliquot lineari-setaceis 

 muniti, apicem versus pubescentes. Folia rudicalia plu- 

 rima, sessilia, linearia, acuminata, glabra, integerrima, v. 

 nunc subruncinata, dentibus paucis, magnis, retrorsis in- 

 structa, 2 — 3-uncialia, sesquilineam lata. Flores citrini, 

 parum minores. Involucrum simplici serie 12-phyllum, 

 cylindraceum, glaucum, tenuissime pubescens, unguicu- 

 lare, basi squamis pluribus (8 — 10) lineari-setaceis, patulis, 

 apice nigricantibus munitum : foliolis linearibus, membra- 

 naceis, sub apice tuberculo auctis. Receptaculum nudum. 

 Ligulcs 5-dentatoe, 6-nervise, involucro fere duplo longiores. 

 AnthercB crista ovali membranaceri coronata?, basi biden- 

 ticulata;. Stigmata brevia, crassiuscula, lineari-lingulata, 

 pruinosa. Achenia matura nondum vidi. Pappus omnino 

 ut in prrecedente. 



The simple polypliyllous involucrum, independent of any 

 other character, is alone sufficient to distinguish Chondrilla from 

 Lactuca, its nearest ally. To the normal group of the genus, 

 besides Chondrilla juncea of Linnasus, belong Chondrilla latifolia 

 and graminea of the " Flora Taurico-Caucasica," and a fourth 

 species contained in the Pallasian herbarium, marked " Pre- 

 nanthes nova," and which possibly may prove to be the Pre- 

 nanthes aspera of Schrader and Willdenow. It is very probable 

 that Chondrilla lavigata of Pursh may prove a third aberrant 

 species of this genus, as the description appears to indicate an 

 intimate affinity to C. Sessaana above described. 



Traciiodes. 



