WOOTON AND STANDLEY FLOEA OF NEW MEXICO. 633 



2. IVA L. Marsh elder. 



Coarse herbaceous perennials or annuals with entire or dissected leaves, at least some 

 of them opposite; heads numerous, small, axillary or loosely paniculate; involucre 

 hemispheric, of few rounded bracts; receptacle with linear or spatulate chaff; marginal 

 flowers pistillate, 1 to 5, their corollas tubular or wanting, the disk flowers perfect, 

 with 5-lobed funnelform corollas; achenes flattened, glabrous; pappus none. 



KEY TO THE SPECIES. 



Perennial; leaves small, entire, sessile; heads axillary 1. /. axillaris. 



Annuals; leaves large, not entire, petiolate; heads not axillary. 

 Heads in terminal bracteate spikes; fertile flowers with evi- 

 dent corollas 2. /. ciUata. 



Heads naked-paniculate; corolla of fertile flowers rudimen- 

 tary or none. 

 Heads conspicuously pedicellate; leaves twice or thrice 



pinnately parted 3. 7. amhrosiaefoUa. 



Heads nearly sessile; leaves toothed or laciniate-pinna- 

 tifid. 

 Stems 1 meter high or more; plants bright green; 



leaves serrate 4. /. xanthiifolia. 



Stems 60 cm. high or less; plants densely tomentose; 



leaves mostly laciniate-pinnatifid 5. /. dealbata. 



1. Iva axiUaris Pursh, Fl. Amer. Sept. 743. 1814. 

 Type locality: "In Upper Louisiana." 



Range : British Columbia and Saskatchewan to California, New Mexico, and Okla- 

 homa. 



New Mexico: Farmington; San Juan; Anniston. Alkaline soil, in the Upper So- 

 noran Zone. 



2. Iva ciHata Willd. Sp. PI. 3: 238G. 1803. 

 Type locality: "Habitat in America boreali." 



Range: Nebraska and Illinois to Louisiana and New Mexico. 



In Plantae Fendlerianae this is said to occur "From Sand Creek, New Mexico, to 

 Fort Leavenworth, in low prairies." We have seen no New ^lexican specimens, but 

 the plant is to be expected in the northeast corner of the State. Plains and dry fields, 

 in the Upper Sonoran Zone. 



3. Iva ambrosiaefolia A. Gray, Syn. Fl. l^: 246. 1884, 

 Ewphrosyne ambrosiaefolia A. Gray, PI. Wright. 1: 102. 1852. 

 Type locality: "Mountains near El Paso," Texas or Chihuahua. 

 Range: Western Texas to southern New Mexico and southward. 



New Mexico: Trujillo Creek; Mangas Springs; mesa west of Organ Moimtains; 

 Organ Mountains; Florida Mountains. Diy mesas and sandhills, in the Lower and 

 Upper Sonoran zones. 



4. Iva xanthiifolia Nutt. Gen. PI. 2: 185. 1818. 

 Euphrosyne xanthiifoHa A. Gray, PI. Wright. 2: 85. 1853. 



Type locality: "In arid soils, near Fort Mandan, &c., on the banks of the Mis- 

 souri." 



Range: Saskatchewan and Nebraska to Washington and New Mexico. 



New Mexico: Cedar Hill; Shiprock; Chama; Pecos; Santa Fe; Sandia Mountains; 

 Mountainair; Taos; Hebron; Las Vegas; Belen. Along streams and in waste ground, 

 in the Upper Sonoran and Transition zones. 



A common weed in cultivated fields in some parts of the State. 



