Apiastrum. UMBELLIFER^. 643 



all radical, tripinnafcly divided ; the segments narrowly linear, acute ; fruit 

 nearly £;lal)n)iis. 



Rocky Mountains, Ntdlall ! — Plant about a span liigli, of a glaucous hue, 

 growinc; in tufts. Leaves divided like those of the Carrot, but niucli smaller. 

 Peduncle much longer than the leaves, with a small crowded umliel of 12- 

 20 rays. Involucel T-O-parted ; the seijments lanceolate. Kruit (immature) 

 oblong-elliptical ; the ribs nearly obsolete : iiUervals with 'J-J conspi<uou8 

 vittai, which are filled with a more aromatic oil than in the species of ilie 

 preceding section. 



Series 3. Seed with the base and tJie apex curved inwards, or sac 

 cately concave. (Subord. C(ELosrERMiE, DC.) 



Tribe XIII. CORIANDREiE. Koch; DC. 



Fruit globose ; or the carpels subglobose and didymous : primary 

 ribs of each carpel 5, depressed and ilcxuous, or nearly obsolete ; 

 the secondary ones 4, more prominent : all wingless. — Umbels 

 compound. 



48. ATREMA. DC. mem. Umb. p. 71, t. 18, S^- prodr. 4. p. 250. 



Calyx-teeth 5, acute, small, persistent. Petals obovate, deeply emar- 

 ginate. Fruit didymous. Carpels subglobose, ventricose, with 4 some- 

 what prominent ribs. Vittae none. Commissure closed. Seed conspi- 

 cuously involute at the base and summit. — An annual herb, with angular 

 stems; the angles, as well as the rays of the umbels and margin of the 

 leaves, muricate-scabrous. Leaves many-cleft, with linear segments. 

 Umbel and umbellets 5-8-rayed. Involucre and involucels of several 

 3-cleft or entire leaflets. Flowers white. Fruit w'lih but little taste, from 

 the absence of vitta;. 



'A. Americana (DC. ! 1. c.) 



Prairies of Arkansas, Nutlall! Dr. Leavenworth! Dr. Hale! Texas, 

 Drummond /—Plant 12-18 inches high, every part, particularly the angles 

 of the stem near eacli leaf and below the umbel, roughened with minute 

 callous points. Segments of the leaves almost capillary. Rays of the 

 umbel about an incli long. Involucellate leaves 2-4, ("entire," DC, but 

 trifid in his figure!) divided to the middle; the segments subulate. Fruit 

 resembling that of Coriander (Coriandrum sativum), but rather smaller : 

 the primary ribs shghtly prominent and somewhat flexuous. 



49. APIASTRUM. Nutt. mss. . 



Margin of the calyx nearly obsolete. Petals somewhat orbicular, entire, 

 concave (not inflexed at the apex). Styles very short. Stylopodium minute. 

 Fruit didymous, much contracted at the commissure. Carpels ovate- 

 globose, with 5 slightly elevated rugulose ribs, and single vittae in the in- 



