258 BOTANY AS APPLIED TO VETERINARY SCIENCE. 
satisfaction to his employer by bringing bis knowledge of 
the science of botany practically into use. 
Leaving for a time the natural order Leguminosa, to 
return to it again when considering the plants whose seeds 
yield a supply of food, I purpose now noticing the plants 
whose stems, leaves, and roots are largely cultivated as 
articles of food for certain classes of our domesticated animals. 
Occupying a prominent position amongst these, are the 
different varieties of the turnip. This plant belongs to the 
class of’ Exogens, and to the sub-class Thalamiftora ( 4< flowers 
furnished with both a calyx and a corolla, the latter consisting 
of distinct petals; stamens always hypogynous or united to 
the sides of the ovary”), and to the natural order Crucifera 
(cressworts), which may be known by the following characters 
—Sepals four, deciduous. Petals four, cruciate. Stamens six, 
of which two are shorter, solitary; and four longer, in pairs. 
Disc with various green glands between the petals, and the 
stamens and ovary. Ovary superior, with parietal placentae, 
usually meeting in the middle, and forming a spurious dis¬ 
sepiment. Stigmas two, opposite the placentae. Fruit a 
silique or silicule, one-celled, or spuriously two-celled, one or 
many seeded ; dehiscing by two valves separating from the 
frame, or indehiscent. Seeds attached in a single row to each 
side of the placenta, generally pendulous. Albumen none. 
Embryo with the radicle folded on the cotyledons. Herbaceous 
plants, annual, biennial, or perennial, very seldom suffruticose. 
Leaves alternate. Flowers usually yellow or white, seldom 
purple, without bracts.”—( Findley .) 
The cruciate arrangement of the sepals and petals, and the 
tetradynamous stamens (four long and two short ones), will 
distinguish this from all other natural orders. 
Good examples of this order may be seen in the wallflower, 
(C heir ant hus cheiri ), which at this period of the year gives so 
much fragrance and beauty to our flower-gardens. This very 
natural assemblage of plants is distributed over most parts of 
the temperate regions of the world. Between two and three 
thousand have been described, and about eight hundred of 
them have been introduced into or are growing w 7 ild in this 
country. Most of the seeds of the plants contain a fixed oil, 
and from some it is expressed and largely used in commerce ; 
such is rape oil. They also contain a pungent volatile oil, 
which renders many of the plants much valued as esculents,such 
as the mustard, horse-radish, and the cresses. It is this stimu¬ 
lating principle which produces the rubefacient properties of 
the mustard, and is also probably the source of the antiscorbutic 
properties which many plants in this order are said to possess. 
