206 
ORCHIDACEAE 
Valley rice-fields; nat. from Enr. Var. zelayensis (H. B. K.) Hitchc. 
A pale short-awned form with short ascending racemes.—Open, often 
alkaline soil, mostly along irrigating ditches, Imperial Co. 
31. HOLCUS L. Sorghum 
Annuals or perennials with flat blades and terminal panicles of 1 
to 5 jointed tardily disarticulating racemes. Flowers perfect and stami- 
nate, borne in the same inflorescence but in unlike spikelets, the sessile 
spikelets with perfect flowers, the pedicellate with staminate flowers. 
Terminal joint with two pedicellate spikelets. (Old Latin name for 
a grass, probably from Greek holcos, attractive.) 
Panicle large, open ; spikelets very small; perennial by spreading rootstocks. 
1. H. halepensis. 
Panicle smaller, denser; spikelets larger; annual.2. H. sorghum. 
1. H. halepensis L. Johnson Grass. Culms 6 to 12 dm. high; 
blades flat, 6 to 18 mm. wide, the midrib prominent, white; panicle 15 to 
25 cm. long, open; fertile spikelets about 5 mm. long, the glumes pubes¬ 
cent, becoming glabrate and shining; fertile lemma with a bent readily 
deciduous awn; staminate spikelets narrow, 4 mm. long, on pedicels about 
3 mm. long, the glumes membranous, nerved, glabrous.—Native of the 
Old World; cult, as a valuable forage grass but often becoming an aggres¬ 
sive weed. (Andropogon halepensis Brot.) 
2. H. sorghum L. Field Sorghum. Cult, from the Old World in 
many forms. Those with juicy pith include Sugar Sorghum and Kafir 
Corn. Those with dry pith include Broom Corn, Milo Maize and Durra 
(including Egyptian Corn). The sorghums are valuable fodder and 
grain plants, but when first introduced into the United States loud- 
sounding and extravagant claims were made by promoters for these 
cereals, whence the significant slang in American politics, Senator Sorg¬ 
hum. The Sudan Grass of cultivation is var. sudanensis (Piper) 
Hitchc.; rootstocks none; branches few; midribs not white. 
32. ZEA L. Maize 
Annuals with broad leaves. Flowers unisexual, the staminate in a 
terminal panicle (the “tassel”) the pistillate in a thick spike surrounded 
by leafy husks (the “ear”). Staminate spikelets in pairs on the rachis, 
one sessile, the other pediceled, each 2-flowered. Pistillate spikelets in 
several close rows upon a greatly thickened axis (the “cob”), consisting 
of one fertile and one sterile flower; styles numerous, protruding from 
the ear and forming the “silk”. (An old Greek name for some common 
cereal.) 
1. Z. mays L. Indian Corn. Native of America and cult, from pre¬ 
historic times. The wild ancestor is not known (cf. Collins, Jour. Wash. 
Acad. Sci. 2:520). Important cultural varieties are sweet, dent, and 
pop corn. 
ORCHIDACEAE. ORCHID FAMILY 
Perennial herbs. Flowers perfect, irregular, bracted, either solitary 
or in spikes or racemes. Sepals 3, alike. Petals 3, 2 alike, the third 
petal called the “lip” commonly dissimilar in color, size and shape, often 
enlarged, sac-like or spurred, in our genera most frequently brought 
