Monographs Details: Isotoma longiflora (L.) C.Presl
Authority: Britton, Nathaniel L. Flora Borinqueña.
Description:Species Description - Acridity is a feature of some plants of the Lobelia Family, due to the narcotic, poisonous principle lobelin, and related substances; it is intense in this low, white-flowered herbaceous plant, distributed nearly throughout the West Indies except the Bahamas and northern Lesser Antilles, ranging also from Mexico to Bolivia and Brazil, and found in Hawaii; it is common at lower elevations in Porto Rico, growing in fields, on banks and hillsides, and, as a weed, in waste and cultivated grounds, in moist or wet districts. The large, long, white flowers are conspicuous; the plant may produce great distress if eaten.
Isotoma (Greek, equally divided), published as a genus by the eminent English botanist Lindley in 1826, has only the species here illustrated in America, the other 7 or 8 being Australasian, if they have all had a common ancestry in the remote past, we may only conjecture in what part of the world this descent took place, and whether our American plant has been derived from an Australasian parent which was transported across the Pacific Ocean, or vice versa. They differ from other genera of the family in that the corolla-tube is not split to the base, and the limb is nearly equally divided, whence the generic name. They are herbs, with alternate leaves, and clustered, or solitary flowers. The limb of the calyx is 5-parted, with narrow segments; the corolla has a long, cylindric tube and a much shorter, spreading, 5-lobed limb; the 5 stamens are borne on the corolla-tube, their filaments more or less united, 2 of the anthers bristle-tipped, the others larger, not tipped; the ovary is 2-celled, with many ovules, the stigma 2-lobed. The capsular fruit is oblong or cylindric, splitting lengthwise into 2 valves, when ripe.
Isotoma longiflora (long-flowered) is perennial, upright, or straggling, little branched, hairy, from 0.2 to 0.6 meters high. The flaccid leaves are oblong, or lance-shaped, stalkless, coarsely toothed, pointed, or blunt, from 6 to 12 centimeters long, with a long-tapering base. The flowers are solitary, and short-stalked in the leaf-axils; the calyx-segments are from 10 to 15 millimeters long; the tube of the corolla is slender, from 8 to 11 centimeters long, its narrow lobes about 2 centimeters long. The oblong, or ellipsoid, nodding capsule is about 1.5 centimeters long.
Lobelia longiflora Linnaeus, Species Plantarum 930. 1753.
Isotoma longiflora Presl. Prodromus Monographiae Lobeliacearum 42. 1836.