244 GENUS ATRIPLEX. 



The transition between the annual and the perennial habit is found in the pentandra 

 group, where the change takes place within several of the subspecies. The character is 

 here useful as adding to the characters which separate the annuals, A. bracteosa and A. 

 wrighti, from the similar but strictly perennial A. linifoUa; also as an additional criterion 

 for separating the annual A. microcarpa from the perennial A. coulteri. The two dioe- 

 cious' herbs following this group are perennials with a somewhat woody base. From 

 here on to the end of the genus all of the species are classed as shrubs, although some of 

 the earlier ones are only subshrubs with herbaceous branches. The distinction between 

 herbs and shrubs is here more useful than in many other genera, because this character 

 runs approximately parallel with the dioecious habit. 



Other features of the habit, such as the method of branching, direction assumed by the 

 stems and twigs, size of plant, and degree of leafiness are of some assistance in distinguish- 

 ing the species and smaller units, but fail as criteria when groups of species are involved. 



GENERIC DIAGNOSIS. 

 ATRIPLEX Linnaeus, Sp. PI. 1052, 1753. 

 Annual and perennial herbs and shrubs, more or less pubescent with inflated scurf-like 

 hairs. Leaves alternate, or the lower opposite, rarely all opposite, sessile or petioled, 

 entire to dentate or irregularly and deeply lobed. Flowers monoecious or dioecious, 

 solitary or in glomerules, the single or clustered flowers in the leaf-axils and often also in 

 terminal spikes or panicles, the staminate and pistillate flowers often mixing in the 

 same cluster, but the staminate usually confined to the upper axils or to terminal inflores- 

 cences. Staminate flowers without bracts or bracteoles; perianth 3- to 5-parted, the 

 segments obovate or oblong and obtuse; stamens 3 to 5, inserted on the base of the per- 

 ianth, the filaments either united at the base or distinct, the anthers 2-celled; rudiment of 

 the ovary conical or wanting. Pistillate flowers each subtended by 2 bracts; bracts 

 accrescent, distinct or usually united at least at the base and inclosing the fruit, entire 

 or the margins variously dentate, sometimes fleshy-thickened or spongious ; perianth none 

 or rarely present and then consisting of a 3- to 5-lobed membranous calyx or of 1 to 5 

 squamellae; disk and rudimentary stamens wanting; ovary ovoid or depressed-globose; 

 stigmas 2, nearly filiform, or slightly thickened or compressed near the base, where also 

 shortly connate; ovule oblique or erect and with a short funicle, or inverted and suspended 

 from the end of an elongated funicle. Utricle inclosed between the bracts, the pericarp 

 membranaceous and usually free from the seed. Seed erect or inverted, rarely hori- 

 zontal, the coats membranaceous, coriaceous or almost crustaceous; embryo annular, 

 surrounding the farinaceous albumen, the radicle inferior, lateral, or superior. 



Artifieial Key to the Species of Atriplex.^ 



Plant an herb, sometimes slightly woody at base, but not shrubby. 



Foliage green or greenish on both surfaces, sparsely mealy and therefore some- 

 times grayish when young. 

 Bracts orbicular or rounded-ovate, 10 mm. or more broad. 



Staminate flowers mixed with the pistillate; leaf-blades 4 to 12 cm. long I. A. hortensis (p. 247). 



Staminate flowers in terminal panicles, the pistillate in the leaf-axils; leaf- 

 blades 1 to 2 cm. long 19. A. graeiliftora (p. 279). 



Bracts not orbicular, less than 5 mm. broad. 

 Fruiting bracts united only near the base; staminate flowers mixed with the 

 pistillate or in very short spikes. 

 Bracts hastate to rounded or cuneate at base; radicle pointing downwards. . 2. A. patula (p. 248). 

 Bracts mostly with rounded ear-like lobes near the base; radicle pointing 



upwards. (Interior species.) 11. A. phylloategia (p. 266). 



Fruiting bracts united to above the middle; staminate flowers mostly in glom- 

 erules of elongated terminal spikes or panicles. 

 Leaves strictly entire; calyx-lobes crested on the back. Rocky Mountains 



to Nebraska and northward 9. A. dioeca (p. 264). 



Leaves mostly sharp-toothed; calyx-lobes smooth. Nevada and Cahfornia. . 29. A. bracteosa (p. 305). 



■ A natural grouping of the species is given in a series of phylogenetic charts to be found on pages 238, 270, 278, 293, 

 and 314. 



