Saltbush leaves: excision of hypersaline tissue by a kangaroo rat.

ABSTRACT

Dipodomys microps climbs into shrubs and harvests leaves of the halophyte Atriplex confertifolia throughout the year. The epidermal vesicles of these leaves are high in electrolyte concentration, but the specialized photosynthetic parenchyma which is arranged concentrically about the vascular bundles is low in electrolytes and high in starch. The lower incisors of D. microps are broad, flattened anteriorly, and chisel-shaped (unlike those of other kangaroo rats, which are rounded and awl-shaped) and are used to shave off the hypersaline, peripheral tissue of the leaves so that the inner tissue can be eaten. This atypical feeding behavior should minimize the reliance of D. microps on the unpredictable seed crops of desert annuals, and also favor its coexistence with other species of Dipodomys, which are primarily granivorous.