PIIARMACAL PLANTS AND THEIR CULTURE. 
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594. Opuntia engelmanni Solm. Prickly pear. Cactacece. 
Fruit is sweet. Large quantities are collected, dried and preserved 
for food by the Indians. 
595. Opuntia tuna Mill. Prickly pear. Cactacece. 
Said to have the properties of Cactus grandiflorus. Cultivated for 
the rearing of the cochineal insect (Parsons). 
596. Opuntia vulgaris Mill. Cactacece. 
Has the properties of the above species. (Proc. A. Ph. A. 32: 179- 
180, 1884.) 
597. Orchis species. Salep. Orchidacece. 
The dried tubers of various species of orchis are known as Salep. 
They are mucilaginous, and highly nutritive. In mediaeval times much 
used as an aphrodisiac, although having no such properties. Well- 
known medicinally in various countries. 
598. Orobanche (Aphyllon) species. Beech drops. Cancer roots. 
Orobanchacece. 
Parasitic plants of which there are many species in California. 
O. uniflora L. and other species are used in intestinal troubles. For- 
merly much used as an application to ulcers, especially to cancerous 
growths, hence the name “cancer root.” “Martin’s Cancer Powder” 
was made of a mixture of cancer root and white oxide of arsenic. 
599. Orobanche (Aphyllon) californica C. and S. Cancer root. 
Orobanchacece. 
Said to be rich in tannic acid. The rootstock of 0 . ludovicianum 
Gray, though bitter, is eaten by Indians (U. of C. Agr. Exp. Sta. Rep., 
1897-1898, page 260.) (Cal. Geol. Surv. Bot. 1:585.) 
600. Origanum vulgare L. Sweet marjoram. Labiatce. 
Well known and extensively cultivated pot-herb used as a spice. At 
one time much used medicinally, as a diaphoretic and emmenagogue, 
and externally as a poultice. Yields the well-known oil of origanum. 
Used as a condiment. 
601. Orophaca (Astragalus) caespitosa Britt. Low milk vetch. 
Leguminosce. 
This plant is reported to be poisonous to cattle. The poisonous con- 
stituents require further study. 
602. Oryzopsis membranacea. Common sand grass. Graminece. 
The seeds are used as food, as a substitute for rice. 
603. “Osha.” 
This name is applied to a root derived from an unknown plant, per- 
haps a species of peucedanum. An analysis of the root was made by 
Dr. Hermann Haupt, who discovered an acid closely similar to angelic 
