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Published In: Bulletin of the California Academy of Sciences 1(3): 72–73. 1885. (Bull. Calif. Acad. Sci.) Name publication detailView in Biodiversity Heritage Library
 

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

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ATHYSANUS Greene, Bull. Calif. Acad. Sci. 1: 72. 1885.

Ihsan A. Al-Shehbaz

Tribe: Arabideae de Candolle, Mém. Mus. Hist. Nat. 7(1): 229. 1821.

Name derivation: Greek, a, not, and thysano, fringe, in reference to the lack of fringe along the fruit margin.

Type species: Athysanus pusillus (W. J. Hooker) Greene (based on Thysanocarpus pusillus W. J. Hooker).

Heterodraba Greene, Bull. Calif. Acad. Sci. 1: 71. 1885. Type species: H. unilateralis (M. E. Jones) Greene (based on Draba unilateralis M. E. Jones).

Herbs, annual, pubescent. Trichomes simple mixed with short-stalked, forked, 3-rayed, or cruciform ones. Multicellular glands absent. Stems ascending, branched at base. Basal leaves short petiolate, not rosulate, simple, entire or dentate; cauline leaves shortly petiolate to sessile, not auriculate, similar to basal ones. Racemes many flowered, ebracteate, corymbose, secund, lax, elongated considerably in fruit, the flowers cleistogamous and/or chasmogamous; rachis straight; fruiting pedicels slender or stout, recurved, persistent. Sepals oblong, free, suberect, caducous, base of lateral pair not saccate. Petals white, rudimentary and much shorter than sepals, rarely absent or well developed and exceeding sepals; blade spatulate to oblong, apex obtuse; claw undifferentiated from blade. Stamens 6, included, erect, subequal; filaments wingless, unappendaged, glabrous, free; anthers ovate to globose, not apiculate. Nectar glands lateral, 1 on each side of lateral stamens; median glands absent. Ovules 212 per ovary; placentation subapical or parietal. Fruits indehiscent or very tardily dehiscent silicles, orbicular or obovate to elliptic, latiseptate, pendulous, not inflated, unsegmented; valves papery, not veined, glabrous or pubescent, sometimes with hooked setae not keeled, smooth, wingless, unappendaged; replum rounded, visible; septum lacking or present and veinless; style obsolete; stigma capitate, entire, unappendaged. Seeds aseriate or uniseriate, wingless, oblong, flattened; seed coat not mucilaginous when wetted; cotyledons accumbent.

 

Two species 2: W Canada, NW Mexico, W United States.

 

 

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                                           Key to the species of Athysanus

1.  Fruits (when pubescent) with hooked trichomes, without a septum, 1-seeded, not twisted,

     indehiscent.............................................................................................................................. 1. A. pusillus

1.  Fruits (when pubescent) without hooked trichomes, with a septum, more than 1-seeded, often

     twisted, tardily dehiscent.................................................................................................... 2. A. unilateralis

 

 
 
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