growth, and, falling off, serve to propagate the plant. In some species of Garlic (Allium) several of the arrested flower-buds become bulbels, which develop young plants in a similar way.

Many of the Liliaceæ are highly ornamental and much prized as garden flowers. Tulips, the numerous species

FIG. 170.-Flower of White Lily.

of Lily, Hyacinths, the Crown Imperial, Asphodels, and Yucca or Adam's Needle, belong to the Order.

Several useful products are derived from the Lily Family, including the drug Aloes, which is the dried juice obtained from the leaves of species of Aloe growing in Africa and the West Indies, and New Zealand Flax, a strong fibre, afforded by the leaves of Phormium tenax, used for cordage, &c.

67. Natural Order-Juncaceæ. The Rush Family. DISTRIBUTION.-A small, widely-diffused, cosmopolitan Order, a considerable proportion affecting cool or alpine localities. British genera 2, species 20.

Herbs. Perianth-leaves scarious; stamens 6. Ovary superior. Type-Field Woodrush (Luzula campestris).

An herb, with tufted grass-like leaves, and slender erect stems, bearing close heads of small, dry flowers.

OBSERVE the scarious perianth and extremely minute embryo, by which the Order is distinguished from Liliaceæ. In general aspect the species of the Rush Family resemble

FIG. 171.-Vertical section of flower of Field Woodrush.

Sedges, but differ from them in possessing a complete six-leaved perianth.

The wick of "Rushlights" is the cellular pith-like tissue of peeled stems of Rush (Juncus effusus). Under the microscope this pith-like tissue exhibits beautifully star-shaped (stellate) cells.

68. Natural Order-Orchidaceæ. The Orchid Family. DISTRIBUTION.-Widely diffused through both hemispheres; especially numerous in humid and warm regions.

A large portion of tropical species are epiphytal.-British

genera 16, species 37.

Herbs. Perianth irregular.

Stamen I (except Cypripedium),

anther gynandrous. Ovary inferior.

FIG. 172.-Flower of Spotted Orchis.

Type-Spotted Orchis (Orchis maculata).

A succulent herb, with a lobed tuberous root, erect leafy stem, and densely spicate pale pink or white irregular flowers.

OBSERVE the partial twisting of the ovary, which renders those parts of the flower which are really posterior apparently anterior: the enlarged 3-lobed lip (labellum), the base of which is continued into a spur, containing a sweet fluid (nectar), sought after by insects; hence the name nectary applied by the older botanists to this and similar spurs the single anther adherent to the pistil, consisting of two more or less parallel lobes, opening in front lengthwise at an early period, and terminating below in a small round knob (the rostellum), which projects over the mouth

st stigma.

of the nectary immediately above the viscid stigmatic surface. The adherent anther, together with the rostellum and stigma, constitute the column of the Orchis flower.

Each anther-lobe contains a pollen-mass (pollinium)— a mass of pollen-grains, held together by internal elastic threads, which tie the pollen to a slender stalk, the caudicle. The caudicle terminates in a minute viscid ball, called the gland, embedded in the rostellum.

Take the very fine stem of a grass, or a finely-pointed pencil, and thrust it gently into the spur of a newly

expanded flower, which has not lost its pollen, just as an insect would insert its proboscis when in search of nectar. It will be found that the pencil does not fail to push against the projecting rostellum, so that the pouch-like membrane of the latter is pressed down, and the pencil comes in contact with the under viscid surface of one or of both of the little glands of the two pollen-masses. On withdrawing the pencil, the pollinia are found adhering firmly to it, for the viscid substance which bathes the glands sets hard in a few seconds when exposed. If the pollinia be carefully watched immediately after they are

FIG. 174. Single pollen-mass of Spotted Orchis, with its caudícle and gland.

FIG. 175.-Seed of same.

withdrawn from the anther, they may be observed to become inclined forwards to such an extent, that if, after the lapse of a minute or two, the pencil be thrust into the nectary of a second flower, the pollinia which adhere to the pencil will strike against the viscid stigmatic surface of the flower, and at least a portion of the pollengrains will adhere to it and fertilize the ovules of the flower. The viscidity of the stigma is sufficient to overcome the strength of the delicate threads which bind the grains of pollen together.

From the peculiar relative arrangement of the pollenmasses and stigma in Orchids, Mr. Darwin has shown that the flowers can be but very exceptionally self-fertilized.