TROPIVOLUM (Neo-Lat., from Gk. rpcnraioc, tropaios, relating to turning or change, from trop, a turning, from 'repent, to turn), NASTURTIUM, INDIAN CRESS, XELLOW LARKSPUR. A genus of the order Geraniacea-, about 35 South American species of beautiful twining or spreading annuals and per ennials, producing orange-yellow and sometimes very dark purple or blue flowers in summer. Many are cultivated for ornamental purposes upon arbors, walls, and trellises. The pickled fruits are sometimes employed as a substitute for capers and the fleshy rootstock of several species as a human food. The best known spe cies is Troptrol um in a ju s, a climbing annual in northern climates, which has long been grown in the United States as an ornamental plant. Dwarf varieties of this species are commonly grown in beds and borders. Troptco/u/n minus resembles the foregoing species, but is of weaker growth and produces smaller flowers. Tropcco
I um Lab iann in, a native of Colombia, is a vig orous climbing species, of which several beauti ful varieties are in cultivation. T ro pa.ul in per cyrinunn, sometimes called canary-bird flower, is grown as an annual in outdoor cultdre and as a perennial in conservatories. 'Fromm/um osunn, which produces scarlet and yellow flow ers in the late summer, yields edible tubers, which are used as food in Peru. In northern climates the tubers are taken up in the fall and kept in a dry place during the winter. The an nual species are grown from seeds sown in the spring in ordinary garden soil. The perennial species are propagated by the tubers or by cut tings of the young shoots grown under glass or by seeds. The perennials prefer a richer soil than the annuals, and they require plenty of moisture.