1898] FLORA OF LOWER SONORAN AND ARID ZONES 129 
a similar quality is shown by the following, also from Dr. 
Havard :*3 
The twisted pod or bean contains a spongy and nutritious pulp, rich in 
sugar, and is used as food by the Mexicans and Indians. 
POLYGONACE-ERIOGONES. 
This group of the Polygonacez, embracing eleven genera, is 
notably characteristic of southern California and the adjacent 
arid regions. Kcenigia is an exception, being an arctic and sub- 
arctic species. Of the remaining ten genera, six are confined 
to southern and Lower California and adjacent islands. Erio- 
gonum, by far the largest genus, is distributed over the whole of 
western United States, although its chief center of development 
is also California. Lastarriza has one species found in both 
California and Chili. Oxytheca has five Californian species, of 
which one is in Chili. Chorizanthe embraces some twenty-five 
Californian species (Euchorizanthe) , of which one is in Chili; 
while there is a peculiarly Chilian group, Chorizanthopsis, of 
about ten species, none of which are in California. 
Southern California appears clearly the center of develop- 
ment of Polygonacee-Eriogonez, and the Chilian representa- 
tives, therefore, may be referred to this region for their 
immediate or more or less remote origin. 
Lastarriea Chilensis, although described as a Chilian plant, is 
evidently Californian originally. It possesses a very wide dis- 
tribution in the coast and hill country of Chili, likewise through- 
out southern California. The plants of the two regions are SO 
nearly identical that a very recent distribution must be sup- 
posed. This has probably occurred in connection with the 
shipping of stock, particularly of sheep, as the plant is especially 
adapted for such means of distribution (1) by the recurved 
hooks of the involucre, and (2) by the easy breaking off of the 
younger parts of the stems. 
Oxytheca dendroidea Nutt. falls in the same category as L. 
Chilensis Remy; and the same may be said of Chorizanthe com- 
