262 GENUS ATRIPLEX. 



7. ATRIPLEX SEMIBACCATA Brown, Prodr. 406, 1810. Plate 39. Fleshscale; 

 Australian Saltbush. 



Prostrate perennial herb, becoming woody at base, the trailing stems sometimes as 

 much as 15 dm. long; branches wiry, not angled, at first mealy, soon glabrate and then 

 stramineous, the bark rough only on very old basal portions; leaves alternate, numerous, 

 short-petioled, elliptic or elliptic-oblong, sometimes slightly spatulate, narrowed at base, 

 acute or obtuse at apex, 1.5 to 3 or 4 cm. long, 0.3 to 1.2 cm. wide, irregularly and remotely 

 repand-dentate or many entire, comparatively thin, gray with a fine dense scurf, or this 

 thinner and the leaves then greenish especially on the upper surface, strongly l-nerved 

 from the base; flowers monoecious, the staminate in small terminal leafy-bracted glo- 

 merules, the pistillate solitary or in few-flowered clusters in the axils of nearly all but the 

 uppermost leaves; perianth either 4- or 5-cleft in the staminate flowers, wanting in the 

 pistillate; fruiting bracts sessile or on short stalks, convex and fleshy when fresh but 

 compressed and nearly flat when dry, rhombic, 3 to 6 mm. long, 3 to 5 mm. broad across 

 the middle, cuneate at base, acute at apex, united only below the middle, the margins 

 denticulate or entire, the sides not appendaged but strongly 3- or 5-nerved (the nerves 

 especially prominent when dry) , fleshy-thickened and turning red in living plants ; seeds 

 of two kinds, one nearly black and only 1.5 mm. long, the other brown, about 2 mm. long, 

 more convex, and with a groove near the margin; radicle lateral. 



Native of Australia; introduced and naturalized in California, Arizona, and southern 

 New Mexico; especially abundant in alkaline soil in the San Joaquin and Imperial Val- 

 leys and the coastal slope of southern California. Type locality, vicinity of Port Jackson, 

 Australia. Collections, all from California, except as otherwise indicated: Rough and 

 Ready Island, San Joaquin County, Berg 28 (UC) ; Marin County, in a salt marsh, Au- 

 gust, 1900, Eastwood (UC); near Bakersfield, October 23, 1919, Hall (CI); roadside near 

 Ballona Lagoon, Los Angeles County, Chandler 2020 (UC); Gardena, Los Angeles 

 County, Braunton 623 (UC) ; Avalon, Santa Catalina Island, Millspaugh 450S (UC) ; near 

 Rincon, Riverside County, Reed S74 (UC) ; La Jolla, Millspaugh 44^7 (UC) ; mesa near 

 Otay, San Diego County, Abrams 3522 (UC); Tucson, Arizona, Jones (Herb. Jones); 

 Mesilla Valley, New Mexico (R); Alamogordo, New Mexico, according to Standley 

 (Contr. U. S. Nat. Herb. 19:204, 1915). 



SYNONYM. 



1. Atriplex flagellaris Wooton and Standley, Contr. TJ. S. Nat. Herb. 16:119, 1913. — Reduced to A. 

 semibaccata by the authors of the proposed species (Contr. U. S. Nat. Herb. 19:204, 1915). 



RELATIONSHIPS. 



This is an Australian species the relationships of. which have not been determined. 

 The lateral position of the radicle and the nearly distinct fruiting bracts suggest that it 

 is one of the more primitive forms. 



ECOLOGY. 



Although an introduced species, Atriplex semibaccata is now so thoroughly at home in 

 California that it plays the ecological role of a native. Its habit of forming large spread- 

 ing mats makes it an effective binder of sand and other bare soils, and hence it is a 

 characteristic dominant of back-strands, sandy fields, and clay slopes, in the coast region 

 especially. Its halophytic nature is indicated by nearly pure communities in saline flats 

 and on sea-cliffs, where it is also often associated with A. lentiformis breweri and species 

 of Suaeda. Owing to the protection it affords against erosion, this species regularly 

 occurs as a relict along the eroding rim of bad lands of the Fernando formation, and is 

 typical of the initial stages of such areas. It readily finds its way into roadsides, fallow 

 fields, and other disturbed places, and it persists in annual grassland, where the dense 

 mats are able to make headway in the competition with wild oats and the brome-grasses. 



