1. Iva frutescens L. 



Bushy perennial; stems 5-35 dm. tall, strigose above, glabrous below; leaves 

 4-12 cm. long, opposite below, becoming alternate in the head-bearing region, 

 ciliolate with usually 5 to 17 teeth on each side, narrowly lanceolate to lanceolate 

 or elliptic to obovate, often petioled, 3-nerved, strigose above and below, 2.5 to 8 

 times as long as broad; bracteal leaves of the head-bearing region linear, mostly 

 entire; heads numerous in leafy panicles; involucre hemispheric, 4-6 mm. broad, 

 2-4.5 mm. high; phyllaries 4 to 6, free, obovate or ovate, sparingly strigulose on 

 the back; pales subtending the staminate flowers linear to narrowly spatulate to 

 oblanceolate; pales subtending the pistillate flowers broadly oblanceolate to oblong 

 or broadly spatulate to elliptic; staminate flowers 6 to 19, with corollas about 

 2 mm. long; pistillate flowers 4 to 6, corolla about 1 mm. long; mature achenes 

 brown, resin-dotted, 1-3.9 mm. long. 



Infrequent in mud flats and shallow water in coastal areas, s.e. Tex., s.w. 

 as far as San Patricio Co., June-Oct.; the species as a whole occurs from N.S. to 

 Tex. along the coast. 



Essentially all our plants are referable to the var. frutescens with their leaves 

 mostly 5 to 8 times as long as broad, the measurements of the flower and head 

 parts approaching the lower limits of those given in the general description and 

 the entire plant usually over 1 m. high. Another variety, the var. oraria (Bartlett) 

 Fern. & Grisc, has been collected rarely at Galveston, the specimens perhaps 

 representing casual introductions. It differs from var. frutescens mainly in being 

 a smaller plant with typically larger elliptic to broadly lanceolate leaves. 



2. Iva axillaris Pursh. Fig. 754. 



Perennial herb from creeping rootstocks; stems herbaceous or ligneous at base, 

 3-6 dm. tall, strigose to villous; leaves opposite or becoming alternate above, 

 subsessile, unlobed, at margins entire, ovate to elliptic or sometimes spatulate, 

 obtuse, indistinctly 3-nerved; leaves of the capitulescence smaller but similar; 

 heads short-peduncled, solitary in the upper bract axils; involucre hemispheric, 

 4-5 mm. broad, about 2.5-3 mm. high; phyllaries 4 or 5, united to the middle or 

 above to form a cup (rarely 1 phyllary free), the tips rounded; pales of staminate 

 flowers oblanceolate to spatulate, those of the pistillate flowers oblanceolate or 

 absent; staminate flowers 8 to 20; corolla 2-2.5 mm. long; mature achenes brown- 

 ish, 2.5-3 mm. long. 



In and about playa lakes, edges of salt marshes and cultivated fields in Okla. 

 (?), the Tex. Panhandle (Bailey and Oldham cos.), N.M. (San Juan, Rio Arriba 

 and Quay cos.) and Ariz. (Coconino and Navajo cos.), Apr.-July; Man., Alta. 

 and Wash. s. to Tex., N.M., Ariz, and Calif. 



3. Iva xanthifolia Nutt. Fig. 755. 



Robust annual; stem 4-20 dm. tall, usually glabrous but sometimes pubescent; 

 leaves of midstem opposite, 7-30 cm. long, 3-nerved, usually scabrous above, 

 strigose or tomentose below, ovate or subcordate, coarsely serrate and sometimes 

 3- to 5-lobed; heads numerous in axillary spikes or panicles and naked terminal 

 panicles, sessile or pedunculate; involucre turbinate, 4-5 mm. broad; phyllaries 5, 

 obovate, acuminate, hispid on the backs; pales subtending the staminate flowers 

 subulate or filiform but sometimes absent in the center of the receptacle, those 

 subtending the pistillate flowers obovate, concave, ciliate; staminate flowers 8 to 

 20, corolla about 2.5 mm. long; pistillate flowers usually 5, corolla 0.5 mm. long 

 or represented only by a small flange at the base of the style; mature achenes 

 obovate, finely muricate, usually dark-brown, about 3 mm. long. 



Infrequent in sandy stream beds and sandy stream margins, n.w. Okla. 

 {Waterfall) and Tex. in the higher parts of the Plains Country, N.M. (San Juan, 



1640 



