Annual herb 0.1 - 1 m tall Stem: erect, unbranched or with a few long branches, relatively slender, soft-hairy or coarsely stiff-hairy below, and usually rough, bristly-hairy above. Leaves: alternate, stalkless, clasping (base reaching around stem), 0.5 - 3 cm long, 0.5 - 2.5 cm wide, rounded, palmately veined, toothed along the edges, and covered with stiff, straight hairs. Floral bracts identical to leaves except for possibly being hairless. Flowers: stalkless, deep-purple to pale lavender, radially symmetric with slightly flared petals, and sitting in the axils of leaves or rounded bracts. There are two types of flowers: the lower, smaller ones (rarely 5 mm long) do not open (cleistogamous), while the upper, larger ones (0.8 - 1.3 cm long) open, and are showy by contrast. Sepals: five, but fused at very base, then separating into slightly flared (or nearly erect), 5 - 8 mm long, narrowly triangular lobes with long tapering tips. Often in the lower, cleistogamous flowers, the sepal lobes are smaller and fewer in number. Petals: five, but fused at base into a short (2 - 4 mm long) tube, then separating into longer, slightly flared, somewhat oblong lobes. In the lower, cleistogamous flowers, the petals are reduced or absent. Stamens: five, with short, hairy-based filaments, and longer (2.5 - 3.5 mm) anthers. Pistil: with a single, two- or three-chambered, inferior ovary; and a single style, which usually ends in a three-lobed stigma. Fruit: a two- or three-chambered, 0.4 - 1 cm long (4 - 7 mm long from cleistogamous flowers, up to 1 cm long from open flowers), elliptic or oblong capsule, which opens by two or three, somewhat elliptic, 0.5 - 1.5 mm wide pores located about midway up, or about 1 - 1.5 mm below the apex. Seeds: many, shiny, tiny (0.5 - 0.6 mm long), plump, and somewhat elliptic, with a bumpy or smooth surface.
Similar species: In our area, Triodanis perfoliata is most similar to T. leptocarpa, but that species has much narrower leaves (under 1 cm wide), longer fruit (0.8 - 2.5 cm), and linear sepals, which curve outwards or are reflexed. All of our plants in the Chicago Region are the typical variety, T. perfoliata var. perfoliata, but to the south there is another variety, T. perfoliata var. biflora, which has the capsule pores near the apex, rather than the middle of the capsule.
Flowering: May to July
Habitat and ecology: Somewhat common in disturbed sites, especially those with sandy soil, but also along railroad cinders, and sometimes in woodland clearings.
Occurence in the Chicago region: native
Etymology: Triodanis is a derivation of the Greek word combination for "three teeth", possibly referring to the pores on the capsule. Perfoliata comes from the Latin prefix per, meaning completely or thoroughly, and foliata, meaning leafy, and together roughly meaning that the leaf completely surrounds the stem.
Author: The Field Museum
From Flora of Indiana (1940) by Charles C. Deam
This species prefers dry, sandy soil and is found in dry, open woods and fallow fields and along roadsides. It is rare in northern Indiana, becoming infrequent to frequent in the southern part of the state.
Kearney and Peebles 1969, Martin and Hutchins 1980
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Native annual herb; stem erect, simple or somewhat branched, 10-50 cm tall, spreading hairy, at least near the base. Leaves: Alternate, 0.5-3 cm long (sometimes wider than long), sessile and clasping the stem, round to cordate, with rounded teeth, hairy on the veins and margins. Flowers: Borne singly or in clusters of two or three in leaf axils; calyx 3-8 mm long; corolla 6-12 mm long, purple to bluish lavender. Fruits: Capsule 5-10 mm long. Ecology: Found on hillsides, under shrubs and in the shade of rocks from 5,000-8,500 ft (1524-2591 m); flowers June and July. Notes: Leaves of this slender annual are hairy, alternate, clasping, and relatively small and rounded; flowers are sessile, purple to blue, and borne in spikes. Ethnobotany: Unknown Etymology: Triodanus is from Greek treis, -three,- and odons, -tooth,- hence -three-toothed.- Perfoliata refers to the stem which perforates the stem. Synonyms: None Editor: SBuckley, 2010
Erect, 1-10 dm, simple or with few long branches, often floriferous to near the base, ±scabrous or hairy at least below; lvs (and floral bracts) sessile and cordate-clasping, rotund-ovate or broader, usually toothed, palmately veined, 0.5-3 cm, nearly as wide, or wider, or some of the lower ones narrower; cal cleft to the hypanthium, the lobes narrowly triangular-acuminate, 5-8 mm in open fls; upper fls with deep purple to pale lavender cor 8-13 mm, the tube 2-4 mm; frs oblong or narrowly obovoid, those of cleistogamous fls 4-7 mm, those of open fls to 1 cm, all bilocular or trilocular; pores usually 1-1.5 mm below the tip of the fr; seeds 0.5-0.6 mm; 2n=60. Various habitats, often in disturbed sites; Me. to B.C., s. to trop. Amer. May, June. (Specularia p.)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.