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Published In: New flora and botany of North America, or, A supplemental flora, additional to all the botanical works on North America and the United States. Containing 1000 new or revised species. 4: 67–68. 1836[1838]. (New Fl.) Name publication detailView in Biodiversity Heritage Library

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Project Data     (Last Modified On 8/10/2009)


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3. Triodanis Raf.

Plants annual. Stems erect or loosely ascending, unbranched or less commonly few-branched, mostly from the basal half. Basal leaves usually absent at flowering. Stem leaves sessile or the lowermost leaves less commonly short-petiolate, the margins entire or bluntly to sharply toothed and often inconspicuously hairy. Inflorescences of solitary axillary flowers or small axillary clusters of 2 or 3(–5), mostly very short-stalked, the leaves subtending flowers essentially indistinguishable from the often relatively few foliage leaves, the whole inflorescence appearing spicate. Flowers epigynous, those at the lower nodes cleistogamous (obligately self-fertilizing and probably apogamous), these smaller than the open-flowering ones, the calyx most often with usually only 3 or 4(–6) lobes, the corolla reduced to short flaps of tissue, the stamens variously reduced but when present failing to dehisce or release pollen, and the style highly reduced and nonfunctional. Calyces in normal flowers actinomorphic, (2–)5(6)-lobed, without appendages. Corollas in normal flowers actinomorphic, broadly bell-shaped to saucer-shaped, (3–)5(6)-lobed, the lobes longer than the tube, usually relatively slender (lanceolate to elliptic), blue, purple, or white. Stamens in normal flowers (3–)5(6), attached to the base of the corolla, the filaments short, dilated and hairy at the base, the anthers distinct, elongate. Pistil with 3 carpels. Ovary totally inferior, with 1–3 locules. Style relatively short, straight, the stigma (2)3-lobed. Fruits ellipsoid to narrowly ovoid, narrowly ellipsoid, or narrowly cylindrical capsules, usually with longitudinal nerves, these sometimes minutely ridged toward the tip, dehiscent by 1–3 lateral pores or slits, glabrous or minutely hairy or roughened along the nerves. Seeds ellipsoid, sometimes somewhat flattened, the surface tan to dark brown, shiny (except often in T. perfoliata). Seven or 8 species, North America, Europe, Asia, Africa.

The center of diversity for Triodanis is in the south-central portion of the United States. Only one species (T. falcata (Ten.) McVaugh) occurs in the Old World. All of the species are winter annuals, germinating in the autumn, overwintering as basal rosettes, and flowering the following spring. The regular production of cleistogamous flowers in Triodanis is distinctive but also occurs in a few species of non-Missouri Campanula. The distinction between Triodanis and Specularia Heister ex A. DC., and whether these should be viewed as separate from Campanula, has been somewhat controversial. The species here recognized as Triodanis originally were included in Campanula and subsequently segregated into Specularia. Triodanis was described as a mostly New World segregate of an otherwise Eurasian Specularia. However, the latter name has disappeared from the botanical literature on Old World plants, as it is a nomenclatural synonym of Legousia J.F. Durande. See McVaugh (1945, 1948), Bradley (1968), and Rosatti (1986) for further discussion. The cultivated Venus’ looking-glass, Legousia speculum Fisch. ex A. DC. (Specularia speculum A. DC.), sometimes is grown in Missouri gardens and differs from Triodanis in its more-branched stems, inflorescences in terminal clusters, and lack of cleistogamous flowers.


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1 1. Stem leaves linear to narrowly elliptic or lanceolate, 5–10 times as long as wide; fruits 1(2)-locular, those that develop from normal flowers straight and strongly ascending but those developing from cleistogamous flowers twisted and/or arched away from the stem, dehiscing by 1(2) pore(s) at or near the fruit tip or by longitudinal slits above the fruit midpoint ... 4. T. LEPTOCARPA

Triodanis leptocarpa
2 1. Stem leaves elliptic to narrowly ovate or ovate, less than 3 times as long as wide; fruits 2- or more commonly 3-locular, all similar in size and shape, straight and strongly ascending, dehiscing by (2)3 pores

3 2. Pores positioned at about the midpoint of the fruit, linear to narrowly oblong ... 2. T. HOLZINGERI

Triodanis holzingeri
4 2. Pores positioned either near the base or near the tip of the fruit, oval to broadly oblong-elliptic or nearly circular

5 3. Seeds 0.8–1.0 mm long, strongly flattened (narrowly biconvex); pores positioned at or near the tip of the fruit ... 3. T. LAMPROSPERMA

Triodanis lamprosperma
6 3. Seeds 0.4–0.7 mm long, slightly flattened (relatively plump); pores positioned either near the tip or below the midpoint of the fruit

7 4. Stem leaves 1.5–3.0 times as long as wide, sessile but not or only slightly clasping the stem; flowers mostly cleistogamous, the normal open-flowering one(s) usually solitary (rarely 2 or 3) at the stem tip; pores positioned at or near the tip of the fruit ... 1. T. BIFLORA

Triodanis biflora
8 4. Stem leaves mostly as long as wide or wider than long, clasping the stem; flowers mostly cleistogamous but normal, open flowers usually 1 per node along the upper 1/3–2/3 of the stem; pores positioned below the midpoint of the fruit ... 5. T. PERFOLIATA Triodanis perfoliata
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