82 



20. THASPIUM Nutt. (irnera, i. 19f),— Perennials (2 to 5 

 feet high ), with ternately di\ide(l lea\es and broad serrate or 

 toothed leaflets (or lower leaves simple), mostl}' no involucre, in- 

 volucels of small bractlets, mostly yellow ilovvers, and all the fruits 

 pedicelled. 



Tho species of Thaiipium are in great confusion. In Gray's Manual 

 T. avreum Nutt. and T, irifoUatnm Gray eacii have an apterous variety. 

 These apterous forms Avere taken from Koch's genus Zizia and placed 

 under the Tlia.spinm species apparently from the close resemblance of the 

 foliage. The fruit characters, however, are abundantly distinct, for the 

 Zizia forms have simply ribbed fruit flattened latterally, the central fruit of 

 the umbellets sessile, and flower in early spring; while T. auretim and 

 T. trifolialum of the Manual have winged fruit flattened dorsally, central 

 fruit pedicelled, and flower lat(> in summer, maturing fruit in the fall. 

 Bentham & Hooker have transferred these apterous Zizia forms to a sec- 

 tion 2>(2/a under C'«m/«, from which genus they differ in the absence of 

 stylopodia, central sessile fruit, more prominent ribs, and Thaspium-Vike 

 foliage. The same authors seem to have made no disposition of T. aurenm 

 of the Manual, unless it went with the apterous variety, while the group of 

 forms under T. trifaliadun Gray, of the Manual, hasbeentaken to represent 

 r. eordatum Torr. & Gray. For this latter species Bentham & Hooker 

 seem to have had in mind only Gray's apterous variety, and so referi-ed it 

 to Carum J^ Zizia as one of the two species. In "Watson's Bibliographical 

 Index the synonym Carum eordatum Benth. & Hook, under T. trifoUatum, 

 is correctly quoted so far as literature is concerned, but apparently should 

 be transferred to T. trifoUatum, var. apterum Gray, to express the real 

 form Bentham & Hooker had in mind. This loaves the Manual forms T. 

 aureum. and T. trifoiiatvm -with its var. o/ro/Jwrpm-eiu/i. unprovided for by 

 these authors, the two apterous varieties only having been used to form 

 the section Zizia under Carum. An explanation of this may be found in 

 the fact that most of the herbarium specimens labeled Thuspium aureum 

 are really the so-called apterous varieties. The true Thanpium forms, with 

 winged fruit, are quite uncommon in herbaria, while the apterous forms 

 are vei'y abundant. 



1. T. aureum Nutt. I.e. Glabrous: radical leaves mostly cor- 

 date, serrate: stem leaves simply ternate (rarely biternate); leaflets 

 ovate to lanceolate, rounded or tapering at base, serrate: umbels 8 

 to l2-rayed; rays % to 1 inch long; pedicels about a line long; 

 flowers deep yellow: fruit globose-ovoid, about 2 lines long, all 

 the ribs equally winged. (Fig. 85. ) 



Thickets and woodlands, throughout the Atlantic States and westward 

 into the Mississippi Valley. Apparently not in Canada, all the specimens 

 so labelled from there being Zizia aurra. Fl. in summer and maturing 

 fruit in late summer or autumn. 



