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Published In: Das Pflanzenreich IV. 105(Heft 86): 159. 1924. (22 Jul 1924) (Pflanzenr.) Name publication detail
 

Project Name Data (Last Modified On 6/29/2009)
 

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CHAUNANTHUS O. E. Schulz in Engler, Pflanzenreich IV. 105(Heft 86): 159. 1924.

Ihsan A. Al-Shehbaz

Tribe: Thelypodieae Prantl in Engler & Prantl, Nat. Pflanzenfam. III. 2: 155. 1891.

Name derivation: Greek chaunos, lax, and anthos, flower, in reference to the lax racemes.

Type species: Chaunanthus petiolatus (Hemsley) O. E. Schulz (based on Thelypodium petiolatum Hemsley).

     Herbs, perennial, sometimes subshrubs or shrubs to 3 m. Trichomes simple, spurred, or stalked and forked. Multicellular glands absent. Stems erect to ascending, often woody at base. Basal leaves not developed; cauline leaves petiolate, not auriculate at base, entire, dentate or denticulate. Racemes many flowered, terminal or lateral at stem apex, ebracteate or rarely lowermost flowers bracteate, corymbose, elongated in fruit; rachis straight; fruiting pedicels horizontal to divaricate or slightly recurved, persistent. Sepals oblong, free, caduceus, erect to ascending, equal, base of lateral pair not saccate. Petals white to pale yellow, erect at base, subequaling or only slightly longer than sepals; blade spatulate to oblong or obovate, apex obtuse; claw undifferentiated from blade, glabrous, unappendaged, entire. Stamens 6, slightly exserted, erect, slightly tetradynamous; filaments wingless, unappendaged, glabrous, free; anthers oblong, not apiculate. Nectar glands confluent, lateral annular, median present. Ovules 10-40 per ovary; placentation parietal. Fruit dehiscent siliques, linear to linear-lanceolate, terete or latiseptate, not inflated, unsegmented; valves papery, with a distinct midvein, glabrous pubescent, not keeled, smooth, wingless, unappendaged; gynophore obsolete or to 0.5 mm; replum rounded, visible; septum complete, membranous, veinless; style distinct, to 2.5 mm, persistent; stigma capitate, entire, unappendaged. Seeds uniseriate, wingless, oblong, plump; seed coat not mucilaginous when wetted; cotyledons incumbent.

 

     Three species: Mexico.

References: Price & Al-Shehbaz (2001), Rollins (1942).

 

 

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                                 Key to the species of Chaunanthus

1. Fruit strongly flattened, long hirsute, attenuate to beaklike apex; stigma sessile;

     racemes lateral, from axils of uppermost leaves ....................................................  3. C. mexicanus

1. Fruit terete, glabrous or minutely puberulent, cuneate to apex; stigma on a distinct style;

     racemes terminal, ebracteate.

     2. Stems hirsute; leaf trichomes exclusively simple; petals 2-3.3 mm wide ..............  1. C. petiolatus

     2. Stems glabrous or puberulent; leaf trichomes stalked-forked at least on abaxial

          surface; petals ca. 1 mm wide......................................................................... 2. C. acuminatus

 

 

 
 
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