308 GENUS ATRIPLEX. 



States that the production of sugar-beets has been abandoned over extensive areas, 

 with the consequent closing down of sugar factories in some districts. The exact nature 

 of the disease is not known, but since it is transmitted exclusively by the beet leaf-hopper 

 (Eutetiix tenella Baker), a knowledge of the habits of this insect is of prime importance. 

 According to Severin, after the beets are harvested the leaf-hoppers pass to certain 

 wild species, the most important of which are the annual Atriplexes. When these 

 dry up in the autumn the insects pass over to the shrubby species, especially those 

 of the foothill canons, where they remain until after the first winter rains, when 

 they leave these plants for the more tender annuals, particularly Erodium cicutarium. 

 The annual Atriplexes are important as host-plants upon which Eutetiix breeds from 

 spring to autumn. Of these, the most important are A. argentea expansa, A. bracteosa, 

 and A. rosea, because of their remaining succulent later in the season than most other 

 species and because of their abundance. It is believed that the considerable 

 increase in the number of these plants as a result of disturbances due to man is 

 largely responsible for the enormous number of leaf-hoppers. The most important 

 shrubby Atriplexes which serve as food plants for the insects in a dry season in Cali- 

 fornia are A. polycarpa and A. spinifera. 



The eradication of the Atriplexes is impracticable, because of their great abundance. 

 It is therefore impossible to control the disease by the destruction of the host-plants of 

 the carrier. However, a knowledge of the distribution and abundance of the different 

 species is an aid in determining the districts where outbreaks of Eutettix are most likely 

 to occur. Such information, therefore, should be used in selecting locations for 

 the culture of the sugar-beet and for the erection of factories. This subject has been 

 discussed in detail by many writers, more especially by Severin and Basinger (Journ. 

 Econ. Ento. 15: 411-419, 1922). 



30. ATRIPLEX LINIFOLIA Humboldt and Bonpland, in WiUdenow, Sp. PI. 4:958, 1806. 

 Plate 47. 



Erect or decumbent perennial herb, 2 to 8 dm. high, the stems curving upwards from 

 a short woody base; branches moderately thick, angled or grooved in the inflorescence, 

 sparsely scurfy, soon glabrate and then stramineous; leaves alternate, crowded, sessile 

 or short-petioled, linear or linear-oblong or some narrowly spatulate, cuneate to attenu- 

 ate at the base, obtuse and mucronate or acutish at apex, 1 to 4 cm. long, 0.2 to 0.5 cm. 

 wide, entire or the larger ones with a few spreading teeth, rather thin, glabrate and 

 greenish on the upper surface, permanently gray-scurfy beneath, 1-nerved; flowers 

 monoecious or partly dioecious, the pistillate flowers in the leaf-axils, the staminate 

 glomerules in nearly naked terminal spikes and panicles, these 5 to 15 cm. long; perianth 

 5-cleft in staminate flowers, wanting in the pistillate; fruiting bracts sessile or short- 

 stalked, compressed, united to above the middle, cuneate-orbicular, the summit always 

 broadly rounded, 2 to 2.5 mm. long, 2.5 to 3 mm. broad, the margins obtusely or acutely 

 dentate above the middle, the faces either tuberculate or crested or unappendaged on 

 the same plant and reticulated or the reticulations masked by the appendages, scarcely 

 scurfy; seed about 1.2 mm. long, brown; radicle superior. 



Mexico, apparently rare. Type locality, Mexico. Collections : Vicinity of Durango, 

 Palmer 349, 350, 495, 496 (Gr, NY, UC, US); alkaUne meadows near Mexico City, 

 PringU 6892 (Gr, NY, UC, US). 



SYNONYMS. 



1. ATRIPLEX POLTGAMA Sesse, in Lagasca, Gen. Sp. Nov. 12, 1816. Apparently the long-leaved form of 

 A. linifolia. Described from Mexican specimens. 



2. Obione linifolia Moquin, Chenop. Enum. 74, 1840. Based upon Atriplex linifolia. 



3. 0. POLYGAMA Moquin, in De CandoUe, Prodr. 13': 114, 1849. Based upon Atriplex polygama, which see. 



