The properties of the Australian plants are only imperfectly known, very few species having been chemically examined; numbers are suspected, but have not been positively proved. The poison plant that caused such havoc amongst the horses of both Jardine and Austin mostly affects the spinifex country. It is a ground plant, and liable to be cropped by a horse amongst the grass, when the animal would probably refuse to touch a bush.
Amongst the most poisonous plants known in Australia may be mentioned the "thorny apple," Datura Stramonium, and Datura tatula; also the Excaecaria agallocha, and Lolium termulentum.
The indigo plant, Swainsona galegifolia, is a glabrous perennial, or undershrub, with erect flexuose branches, sometimes under one foot, sometimes ascending, or even climbing, to the height of several feet. The flowers are rather large, and deep-red in the original variety; pod much inflated, membranous one to two inches long, on a stipe varying from two to six lines. The species varies, with light, purplish-pink flowers, S. coronillaefolia; and white flowers, S. albiflora. The difference in the length of the stipes of the pod does not, as had been supposed, coincide with the difference in the colour of the flower. This plant acts in a peculiar way upon sheep, driving them insane until death ensues. The sheep, however, select it as an especial tit-bit, it, apparently, possessing an irresistible fascination for them.
The "Darling pea" Swainsona procumbens. Glabrous; or the young shoots and foliage slightly silky; or sometimes pubescent, or hirsute, with procumbent ascending, or erect stems of one to three feet. Leaflets varying from oblong or almost linear, and one-quarter inch to half-inch long, to lanceolate, or linear-acute, and above one inch long. Flowers: large, fragrant, violet, or blue; pod sessile, above one inch long.
The "Pitchuri plant," Anthocercis Hopwoodii. A glabrous tree, or shrub. Leaves: narrow-linear, acutely acuminate, with the point often recurved, entire, rather thick, narrowed into a short petiole, two to four inches long; fruit unknown.
"Australian Tobacco," Nicotian suaveolens. An erect annual, or biennial, of one to two feet. Flowers: white, or greenish on side; sweet-scented, especially at night.
Amongst those that are but slightly poisonous are: Typhonium Brownii, and Colocasia Macrorrhiza; the Crinum flaccidum and C. pendunculatum, both bulbous herbs; Carcumbum populifolium and C. Stillingiaefolium, tall shrubs; Duboisea myoporoides and D. Leichhardtii, shrubs; Aristolochia praevenos, a tall, climbing shrub; A. pubera, a small, prostrate, or trailing herb; Chamae fistula laevigata and C. Sophera, erect, glabrous shrubs.
The "Nightshade," Solanum Nigrum. An erect annual, or biennial, with very spreading branches, one to nearly two feet high. Leaves: petiolate, ovate, with coarse, irregular, angular teeth, or nearly entire, one to two inches long. Flowers; small and white, in little cymes, usually contracted into umbels on a common peduncle, from very short, to nearly one inch long. Berry: small, globular, usually nearly black, but sometimes green-yellow, or dingy-red.
The "Bean tree," Castanospermum Australe. A tall, glabrous tree; pods eight or nine inches long, about two inches broad; the valves hard and thick, the spongy substance inside dividing it into three to five cells each, containing a large, chestnut-like seed.
(See page 241.--[Chapter XI.])