UMSELLIFHR2E. 



135 



Fig. 149. Face of 

 mericarp. 



Fig. 150. Back of 

 mericarp. 



natives of the mountains of the warm western regions of the two 

 Americas. 



Tfachydium (fig. 149, 150) consists of annual or perennial herbs, 

 of temperate Asia, chiefly the mountains of northern India, whose 

 characters are mostly those of 



the preceding genera, but the Trachyditm soyui. 



fruit, oval compressed and hollow 

 on each side of the commissure, 

 is furnished with a bifid or bi- 

 partite carpophore, and sur- 

 mounted by a conical depressed 

 or elongate disk. The ridges 

 are obtuse, covered with rugose, 

 papillose or irregular vesicular 

 prominences, and the exocarp 

 separates in the form of a 



floating membrane, from the deep bed of the pericarp. In each 

 furrow are from one to three vitt«, and the seed has a concave face, 

 traversed only by a vertical furrow in Eremodaucus, which forms a 

 section of that genus of which the carpophore is believed to be 

 undivided. 



Near Goniwn, with a fruit more elongate and similar to that of 

 Carum, Musenium, comprising perennial and csespitose herbs of North 

 America, has no involucre, umbels with numerous bracteoles, with a 

 central flower generally more developed than those at the sides, a 

 separating carpophore, numerous vittSB, a channeled seed with 

 concave face, white or yellow petals with inflexed point, unequal 

 persistent sepals, the two larger crowning the anterior mericarp. 

 Musenium has decompound pinnate leaves with pinnatifid segments ; 

 the flowers are white or yellow, and the fruit is covered with short 

 rugose hairs. Tauschia also consists of small American perennial 

 plants similar to Musenium. The radical leaves are pinnate or bi- 

 pinnate with oval or dentate segments. The fruit, oval and com- 

 pressed perpendicular to the partition, resembles that of certain 

 Arracacias. It is glabrous, with equally prominent ridges and solitary 

 vittaB in the furrows. The stylopods are depressed and the carpo- 

 phore is undivided. It disappears or remains adnate to the mericarps 

 in Erigenia, a low North American herb, the subterranean portion of 

 which is a small tubercle from which spring some decompound 



