CL.— THE WOOD SORREL. 
Oxalis Acetosella Linne. 
T HE whole Order Geraniales, with its generally conspicuous, honey-yielding 
flowers, adaptations — often complex — for insect-pollination and for seed- 
dispersal, suggests a high grade in the scale of evolution with its concomitant a 
comparatively modern geological date of origin. This is even more especially true 
of the Family Oxalidacece, for very few groups in the Vegetable Kingdom present 
such elaborate adaptations in all parts of their structure alike. The Family 
comprises some 330 species in seven genera, mostly tropical or sub-tropical, but 
two-thirds of the species belong to the genus Oxalis. Most of them are perennial 
herbs, with scattered, exstipulate, compound leaves, usually exhibiting nyctitropic 
movements. Their flowers are usually rather large, polysymmetric, perfect, and 
pentamerous, with a persistent, imbricate calyx, two whorls of monadelphous stamens 
(those of the outer opposite to the petals), introrse anthers, five carpels united below 
and superior, but with free styles, and the anatropous ovules with ventral raphe 
and micropyle pointing upward which characterise Geraniales. The fruit is usually 
capsular, not beaked as in Geraniacece, but splitting loculicidally, i.e. down the midribs 
of the carpellary leaves, without any detachment of valves. The seeds are usually 
enclosed in fleshy arils which grow up from their bases and exhibit most remarkable 
elasticity. 
The name of the genus Oxalis, from the Greek o£u5, oxus, acid, occurs in Pliny, 
but is applied by him to the Sheep’s Sorrel ( Rumex Acetosella Linne) ; whilst the 
specific name of our common species Acetosella, a diminutive from the Latin acetosus, 
acid, which was the old druggist’s name for the plant, also refers to the abundance of 
oxalic acid which it contains, especially in its leaves, combined with potash. 
Most of the species are South American or South African ; but their great 
powers of scattering their seed have given three or four species a very wide 
distribution. Our Wood Sorrel ( Oxalis Acetosella Linne) occurs over the whole of 
the Palaearctic and Nearctic Regions, and extends to altitudes of 4,000 feet in the 
Scottish Highlands. There are a few shrubby forms ; but most species are small, 
with some kind of underground stem or other food-store. Several South American 
species, such as 0. tuberosa Molina and 0. crenata Jacquin, produce starchy tubers 
resembling small yellow potatoes, which are eaten under the name of Oca: the 
Mexican 0. Deppei Loddiges bears scaly bulbs ; and in our own Wood Sorrel, which 
has a slender rhizome, food is mainly stored in the persisting bases of the leaves. 
Though the leaflets are sometimes altogether absent — the leaf being then 
represented by a flattened phyllode, as in O. msciformis Mikan — or may be reduced 
to two or one, the ternate leaf of our species is generally characteristic of the genus. 
As we see them in our own woods, they rise from the underground stem, in early 
spring, on translucent, red-tinged, hairy petioles. The delicate leaflets, at first of a 
