frequently underlain with a hardpan. The Shadscale Scrub plant 

 community occurs on mesas and flatlands at elevations of 3,000 

 to 6,000 feet (9 14 to 1 ,829 m) in various parts of the transmon- 

 tane desert regions such as the Owens Valley and the Mojave 

 Desert. It is uncommon in the Colorado Desert areas, which are 

 occupied chiefly by Creosote Bush Scrub. Rainfall in these areas 

 is very low — averaging less than 7 inches (17.8 cm) per year. 

 Summers are dry and hot. 



Perhaps the most interesting feature of this plant community 

 is the pecuHarity of the common names given to its component 

 shrubs. Otherwise, as Munz and Keck state, it covers "large mono- 

 tonous areas between Creosote Bush Scrub and Joshua Tree Wood- 

 land", both of which communities are clearly esthetically pref- 

 erable to the Shadscale Scrub. 



Alkali Sink Scrub (Plate 15A-C; Map 3) 



Another scrub community of arid regions is the Alkali Sink Scrub 

 plant community. This community is made up of halophytic 

 shrubs that belong largely to the Goosefoot family (Chenopodi- 

 aceae), a family whose members are salt-tolerant. Characteristic 

 species of the Alkali Sink Scrub plant community are saltbush 

 {Atriplex spp.). Iodine Bush (Allenrolfea occidentalism Plate 15C), 

 pickleweed (Salicomia spp.), Greasewood {Sarcobatus vermicula- 

 tus), and seep weed (Suaeda spp.). All these genera are members 

 of the Chenopodiaceae. Note that Suaeda and Salicomia are 

 also present in the Coastal Salt Marsh plant community, which is 

 not surprising in view of their high salt tolerance. 



The Alkali Sink Scrub occupies the low-lying, poorly drained 

 alkali flats and playas in the San Joaquin Valley (especially 

 around Tulare Lake) and also occurs in similar habitats in trans- 

 montane deserts such as those in the Panamint and Death valleys. 

 The rainfall in such areas may be as low as 2 inches (5 cm) per 

 year or less, but the soil is often saturated with highly saline 

 water for much of the year due to seepage into these low areas. 

 Summer temperatures in these desert regions may be excessively 

 high (as they are, for example, in Death Valley). As might be 

 expected in view of their halophytic nature, Alkali Sink Scrub 



no 



