OXYCOCCUS 
497 
Ourisia Comm, ex Juss. Scrophulariaceae (ill. 10). 19 sp. S. temp. 
Ourouparia Aubl. = Uncaria Schreb. 
Ouvirandra Thou. = Aponogeton Thunb. 
Oxalidaceae. Dicotyledons (Archichl. Geraniales). 7 gen. with 250 
sp, mostly trop. and subtrop. Most are perennial herbs with alt* 
often compound exstip. leaves and large firs., usually in cymes. Fir. 
$ , regular. K 5, imbricate, persistent; C 5, twisted or imbricate, free 
or slightly united ; A 10, obdiplostemonous (i.e. the outer whorl opp. 
to the petals, the inner to the sepals, and thus the cpls. opp. to the 
petals, instead of to the sepals, as in diplostemonous firs, with two 
whorls of sta. in proper alternation), united below, with intro rse 
anthers; G (5), with free styles, 5-loc., with axile placentae; ovules in 
1 or 2 rows in each loc., or few, anatropous, with micropyle facing 
upwards and outwards. Fruit a capsule or berry; embryo straight, in 
fleshy endosperm. Chief genera : Oxalis, Biophytum, Averrhoa. 
The order is closely allied to Geraniaceae, to which it is united by 
Benth.- Hooker. The chief difference is in the fruit. Warming places 
it in Gruinales. 
Oxalis Linn. Oxalidaceae. 220 sp. cosmop. chiefly S. Afr., Am. 
O. Acetosella L. (wood-sorrel) in Brit. It is a small herb with mono- 
podial rhizome and ternate leaves, which sleep at night and in cold 
weather, the leaflets bending downwards. The flr. is protandrous; 
the stalk bends downwards and the flr. closes in dull or cold weather. 
Cleistogamic firs. (cf. Viola, and see p. 98) occur, sometimes, it is 
said, below ground. The fruit is a loculicidal capsule. The seed has 
a fleshy aril springing from the base. When ripe the cells of the 
inner layers are extremely turgid, and a small disturbance causes the 
aril to turn inside out, as one might turn a glove-finger, from U to 
p|. This is done instantaneously and the seed is shot off to some 
distance. 
Many sp. have bulbous or tuberous stems. Some, e.g . O. bupleuri - 
folia A. St. Hil. have phyllodes in place of the ordinary leaves (cf. 
Acacia). The firs, are solitary or in cymose infls. Many sp. exhibit 
trimorphic heterostyled firs, (see Darwin Forms of Firs.) ; there are 
three stocks of plants, one bearing firs, with long styles, and mid- and 
short-length sta., the others with mid or short styles and correspond- 
ingly long and short or long and mid sta. (cf. Lythrum). Some sp. 
produce axillary bulbils: others reproduce vegetatively by under- 
ground offshoots. [See Hildebrand’s Lebensverhciltnisse d. O.-arten, 
Jena, 1884.] The tubers of O. Deppei Lodd. (S. Am., Mex.), and 
others, are used as food. 
Oxera Labill. Verbenaceae (iv). 12 sp. New Caled. 
Oxybaphus L’Herit. Nyctaginaceae. 12 sp. W. Am., Himal. United 
to Mirabilis in Nat. Pfl . 
Cxycoccus Tourn. ex Adans. = Vaccinium Linn. 0 . palustris Pers. = 
V, Oxycoccus. 
W. 
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