glabrous or puberulent, solitary or in 3's or 4's; basal leaves very long, glabrous, 

 linear-lanceolate, 2-4 dm. long, 3-5 mm. broad; leaves of the slender spikes 

 narrowly linear, becoming abruptly shortened, erect and bractlike; heads numer- 

 ous, loosely covering 1-2 dm. of the erect spikelike head-bearing region, with 

 3 to 5 flowers, cylindrical but narrowed acutely to the tip when in bud, about 

 1 cm. long; phyllaries few, glabrous, appressed, the outer ovate, the inner oblong- 

 lanceolate, sometimes becoming purplish; corolla 8-10 mm. long, purple, lacking 

 any pilosity within the tube; achene 4-5 mm. long; pappus about 7 mm. long, 

 barbellate. 



Frequent in often wet areas, e. and s.e. Tex., w, to Austin Co. and s. to Calhoun 

 Co., July-Dec; also La. 



3. Trichocoronis Gray 



Annual or perennial glabrous herbs 5-30 cm. tall, freely branching from the 

 base and rooting at the lower nodes; most of the leaves opposite, only a few 

 upper ones becoming alternate, sessile, 1-3 (-6) cm. long, often shallowly to 

 deeply incised into 3 lobes nearly to the tip but otherwise entire and oblong to 

 cuneate; heads singly terminating the branches; involucres hemispheric, 2-6 mm. 

 high; phyllaries linear or oblong, in roughly 2 subequal series, weak and thin 

 and each obscurely 3-nerved; receptacle slightly convex, naked; ray flowers absent; 

 disk flowers perfect, fertile, numerous, the corollas whitish or purplish-white, 

 sharply divided into a minute glandular-pubescent tube and an abruptly flaring 

 5-toothed limb; achenes 1-2 mm. long, slightly flattened, 5-ribbed at maturity, 

 glabrous, linear, dark; pappus essentially absent or of a few very minute fimbrillate 

 scales. 



A genus of 2 species, both occurring in Texas. 



1. Achenes about 1 mm. long and involucre about 2 mm. high 



1. T. Wrightii. 



1. Achenes about 2 mm. long and involucre about 5 mm. high 2. T. rivularis. 



1. Trichocoronis Wrightii Gray. Fig. 745. 



Depressed annuals (?) with fibrous roots, usually spreading so that the diameter 

 of the clump is greater than the height of the plant; leaves usually oblong, only 

 obscurely toothed near the apex; involucre about 2 mm. high; corolla about 1 mm. 

 long; achenes about 1 mm. long. 



Local in moist swales, calcareous clay soil, Rio Grande Plains and s. part of 

 s.e. Tex. (also Gonzales Co.), spring; also Tam.; adv. in CaHf. 



2. Trichocoronis rivularis Gray. Fig. 745. 



Much-branched and rooting at the nodes, spreading or sprawling; leaves often 

 flaring and slightly lobed apically; involucre usually 5-6 mm. long; corolla 2-3 

 mm. long; achenes about 2 mm. long. Shinnersia rivularis (Gray) King & Rob. 



Very rare and local in moist spring-fed swales and rooted and submersed in 

 streams in n.e. part of Rio Grande Plains and s. part of Edwards Plateau in 

 Tex., spring; also Coah. 



4. Mikania Willd. 



An American genus of about 175 species. 

 1. Mikania scandens (L.) Willd. Climbing hemp-weed. Fig. 746. 



Perennial twining vine; leaves opposite; blades elongate-deltoid, acute, (2-) 

 3-10 cm. long, marginally undulate or shallowly lobed, basally often slightly cor- 

 date; petioles about half as long as blades; heads in corymbiform aggregations at 

 the ends of the branches; phyllaries 4, lanceolate, a few mm. long, equal, often 



1599 



