GERANIACEAE 
63 
1. H. lupulus L. Common Hop. Rough hairy perennial herb; leaves 
heart-shaped, 3 to 7-lobed; staminate panicles 4.8 to 14.4 cm. long; hops 
oblong or ovoid, papery, straw-yellow, glandular.—Native of Eur., cult, 
for the pistillate catkins or hops, which possess an aromatic bitterness 
or lupulin derived from the yellow glands appearing on the ovary and 
base of the bracts. Hops are used medicinally and also in the manufac¬ 
ture of beer, one of the most talked of beverages in America. 
ZYGOPHYLLACEAE. CALTROPS FAMILY 
Herbs or shrubs, ours with opposite pinnate leaves. Flowers perfect, 
regular. Sepals 5. Petals 5. Stamens 10, inserted with the petals on 
the receptacle.—Species about 160, widely distributed in warm and 
tropical regions. 
1. TRIBULUS Tourn. Caltrops 
Herbs, ours annuals. Flowers yellow, solitary on the peduncles. Ovary 
5-celled; cells 3 to 5-ovuled. Fruit lobed, splitting into 5 nutlets. (Greek 
tribulos, ancient name of Trapa.) 
1. T. terrestris, L. Puncture Weed. Stems branching from the 
base, trailing, 1.4 to 8.6 dm. long; herbage whitish-pubescent; petals 2 
to 4 mm. long; nutlets warty on back and with 2 stout spreading spines.— 
Nat. from Eur., following railway lines, thence spreading as a serious 
pest in valley lands. The spiny fruits puncture auto tires. 
OXALIDACEAE. OXALIS FAMILY 
Herbs with alternate or basal 3-foliolate leaves and regular flowers. 
Sepals 5. Petals 5. Stamens 10, united at base. Styles 5. Ovary 
superior, 5-celled, becoming a 5-lobed pod.—Species 230, tropical and 
subtropical. 
1. OXALIS L. Wood Sorrel 
Juice sour. Leaflets inversely heart-shaped, closing and drooping at 
night. Peduncles axillary, few to many-flowered. (Greek oxus, sour, 
the juice containing oxalic acid.) 
1. O. comiculata L. Yelllow Sorrel. Stems decumbent, 7 to 24 
cm. long, bearing alternate leaves; peduncles axillary, bearing a 2 or 3- 
flowered umbel with small bracts; flowers yellow.—Lawns and vacant 
lots. 
2. O. oregana Nutt. Redwood Sorrel. Leaves all basal; peduncles 
scape-like, commonly 1-flowered, 2-bracted near the top; flowers white, 
pink or rose-color, 1.8 to 2.4 cm. long.—Shady places, Redwood belt. 
GERANIACEAE. GERANIUM FAMILY 
Ours annual herbs with at least the lower leaves opposite. Flowers 
regular, on axillary peduncles, with 5 sepals, 5 petals, and 5 or 10'sta¬ 
mens. Ovary superior, deeply 5-lobed, with the 5 styles united around a 
central much elongated axis, the parts of the ovary separating elastically 
when ripe into achene-like fruits bearing the persistent styles in the form 
of long twisted or coiled tails.—Species 360, widely distributed over the 
whole globe. 
