1922] 



PAYSON — STUDY OF THELYPODIUM AND ITS IMMEDIATE ALLIES 261 



Nelson, Manual Cent. Rocky Mountains, 209. 1909, in part; 

 Hayek, Beih. Bot. Centralbl. 27 1 : 184. 1911; Rydb. Fl. Rocky 

 Mountains, 366. 1917, in part. 



Macropodium Hook. Bot. Misc. 1: 341. 1832, in part; Hook. 

 Fl. Bor. Am. 1 : 43. 1840, not R. Br. 



Pachypodium Nutt. in Torr. & Gray, Fl. N. Am. 1 : 96. 1838, 

 not Webb & Berthel. ; Benth. & Hook. f. Gen. PL 1 : 81. 1862. 



Pleurophragma Rydb. Bull. Torr. Bot. Club 34: 433. 1907; 

 Wooton & Standley, Contr. U. S. Nat. Herb. 19: 267. 1915; 

 Rydb. Fl. Rocky Mountains, 368. 1917. 



Biennial or perennial herbs with differentiated radical and 

 cauline leaves and usually erect, simple or branched stems. 

 Trichomes absent or unbranched. Stem-leaves frequently sagit- 

 tate at the base. Flowers purple, lilac, roseate or white; sepals 

 scarcely if at all saccate; petals linear, oblong or oblanceolate, 

 entire; anthers frequently apiculate. Inflorescence usually race- 

 mose, rarely corymbose. Pods terete or slightly flattened parallel 

 to the partition, distinctly stipitate or sessile, 1.5-10 cm. long, 1-2 

 mm. wide, horizontal to erect; style short, stigma small, entire 

 or very slightly 2-lobed. Cells of the septum elongated parallel 

 to the replum in the middle, usually more or less tortuous, shorter, 

 and walls usually less closely compacted near the margin; this 

 central region of elongated cells frequently appears under a hand 

 lens as a broad mid vein. Seeds not winged, cotyledons usually 

 obliquely incumbent. Generic type: T. laciniatum (Hook.) Endl. 



Key to the Species 



A. Cauline leaves sagittate or amplcxicaul at the base, 

 a. Stipe about 2 mm. long; flowers red-purple; in- 

 florescence dense, racemose, pedicels horizon- 

 tal 



1. T. eucosum 



b. Stipe usually less than 2 mm. long. 



I. Biennials or short-lived perennials. 



*Kaceme dense, narrow, spike-like; pedicels 

 rarely over 5 mm. long. 



1. Pedicels stout, divergent, 1-2 mm. 



long B. T.tr achy car pum 



2. Pedicels slender, erect, 3-5 mm. long 3. T. crispum 

 **Raceme lax and narrow or, if dense, corym- 

 bose and broader; pedicels usually more 



than 5 mm. long. 



1. Petals spatulate or broader. 



0. Inflorescence distinctly racemose. 



x. Radical leaves lyrately 



toothed; plants native to 



Oregon and California 4. T.Howellii 



y. Radical leaves entire; plants 

 native to Utah, Arizona 

 and New Mexico. 



