in cottage gardens: the anthers of Potato opening by pores at the apex: the albuminous seeds with, usually, a curved embryo: the fruit of Thorn-apple (Datura), 4-celled, owing to the infolded dorsal sutures of the carpels, which reach and adhere to the placentas.

Although some species under cultivation are amongst our most valuable food-producing plants, the Order is dangerous, including the Deadly Nightshade (Atropa Belladonna), the berry of which, about the size and colour of a black cherry, has often proved fatal to children; Henbane (Hyoscyamus niger), a viscid weed of waste places about villages, with dingy, purple-veined, yellow flowers; and Tobacco (Nicotiana), the oil distilled from which is a virulent poison.

The narcotic principle of Tobacco is developed in the leaf by a fermentative process, after it has been collected. In 1877, upwards of forty-nine millions of pounds of Tobacco were entered for home consumption. It is extensively grown in hot countries, especially in the Southern States of America, Cuba, South America, and the East Indian Islands.

The Potato-plant (Solanum tuberosum) is by far the most important member of the Order, affording our most valuable esculent. It was originally introduced from the south-western coast of South America. Potatoes are the tubers or swollen portions of underground branches, and not roots, as the "eyes" (leaf-buds) of the tubers show. They contain about fifteen per cent. of starch, which may be roughly separated from the tissue of the Potato by grating and washing. From this starch are prepared dextrine, used in calico printing, and British gum, used to attach postage labels. The Potato disease is caused by a minute fungus which usually attacks the leaf in the first place, rapidly descending to the tubers. The starch of diseased tubers, while it remains, is perfectly wholesome.

Cayenne pepper is the ground seeds of species of Capsicum.

The fruits of the Aubergine (Solanum Melongena) and Tomato (Lycopersicum esculentum) are used in cookery. The berry of Winter Cherry may be safely eaten it is cooked in Spain and Germany.

47. Natural Order-Scrophulariacea. The Scrophularia Family.

DISTRIBUTION.—Widely diffused through both hemispheres, from the arctic zone to the equator.—British genera 13, species 50.

Herbs.

Corolla irregular.

Stamens fewer than corolla-lobes

(except Verbascum). Ovary 2-celled.

Type-Common Toadflax (Linaria vulgaris).

An erect perennial herb, with numerous alternate narrow entire leaves, and a terminal raceme of irregular yellow flowers.

OBSERVE the spurred corolla of Linaria; there is normally one spur, but the corolla occasionally becomes 5-spurred and regular. Such regular forms of corollas, normally irregular, are termed Peloria.

Compare, as to form of corolla :-Speedwell (Veronica), in which it is 4-partite, nearly regular and rotate; Mullein (Verbascum), 5-partite and rotate; Foxglove (Digitalis), inflated-tubular; Snapdragon (Antirrhinum), bilabiate and personate; Lousewort (Pedicularis), bilabiate and ringent (gaping); Garden Calceolaria, calceolate or slipper-shaped."

66

Compare, as to number of stamens :-Speedwell, diandrous; Toadflax, didynamous; Figwort, also didynamous, with a rudimentary fifth stamen (staminode); Mullein, pentandrous.

A partial parasitism occurs in some species allied to the Rattle (Rhinanthus) and Eyebright (Euphrasia), as may be ascertained by carefully washing away the soil from the roots. When raised from seed, apart from the plants upon which they prey, though capable of germination they do not grow more than an inch or so in height,

FIG. 130.-Vertical section of flower of Common Toadflax, showing the spur. The corolla is per

sonate.

FIG. 131.-Monstrosity (Peloria) of Common Toadflax, in which 5 spurs are developed, so that the corolla is regular.

and produce but one or two flowers. It is not precisely ascertained what amount or kind of nourishment the nurse-plants yield. Cow-wheat (Melampyrum), Eyebright, Bartsia, and Rattle are suited to experiment upon with a view to further information.

The Family includes very few useful plants, though many are highly ornamental and common in cultivation, as Calceolaria, Pentstemon, Snapdragon, Monkey-flower and Musk (Mimulus), Speedwells, &c. Foxglove is very poisonous, and is used in medicine; a yellow dye is

O. B.

obtained from common Toadflax, and from some Calceolarias.

48. Natural Order—Labiatæ. The Labiate Family.

DISTRIBUTION.-Numerous in every quarter of the globe; especially so in proportion to other Natural Orders in the Mediterranean region.-British genera 18, species 44.

Herbs. Corolla irregular. Stamens fewer than corolla-lobes. Ovary 4-lobed, style from between the lobes.

Type-White Deadnettle (Lamium album).

A coarse perennial herb, with square stem, opposite exstipulate leaves, and axillary cymes (forming verticillasters) of bilabiate white flowers.

OBSERVE the square stem and invariably opposite leaves of the Order, which derives its name from the characteristic form of the corolla of its members. It is irregular and usually two-lipped; hence called labiate or bilabiate.

From those Scrophulariacea which have a similar corolla, Labiates may be distinguished by the ovary, which is 4-lobed as in Boragineæ, each lobe with I ovule, and by the gynobasic style. Labiates differ from Borages in the stamens being fewer than the lobes of the corolla, and in the characters of the stem and leaf referred to above.

Observe, also, the stamens of Sage (Salvia), remarkable for the great length of the connective-the portion of the anther connecting the pollen-containing lobes. In Labiatæ the connective is usually dilated, so that the anther-lobes, instead of being parallel, are divergent at the base, or even in a straight line, as in White Deadnettle; but in Salvia this dilatation is carried to such an excess that the connective becomes much longer than the

FIG. 132.-Vertical section of bilabiate flower of White Deadnettle.

FIG. 133.-Epipetalous stamen of Sage, showing the very short filament and long (distractile) connective. The lower antherlobe is abortive. Rudiments of two suppressed stamens are also shown,

filament, for which it is apt to be mistaken; one of the separated anther-lobes becoming more or less abortive.

None of the Order is hurtful, and many species are aromatic, from the presence of essential oil contained in glands immersed in the tissue of the leaves. The oil may be separated by distillation. In this way Oils of Peppermint, Lavender, Thyme, and Rosemary are obtained. Lavender-water is prepared by dissolving the Oil of Lavender in spirits of wine. Many Labiates are valuable kitchen-herbs, as Mint (Mentha), Penny-royal (Mentha Pulegium), Marjoram (Origanum), Thyme