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Draba sobolifera

(Stolon Whitlow-Grass)

Overview

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Threatened
Threat status

Common Names

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Common Names in English:

Stolon Draba, Stolon Whitlow-Grass

Description

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Family Brassicaceae

Herbs annual , biennial, or perennial , sometimes subshrubs or shrubs , with a pungent , watery juice. Eglandular trichomes unicellular, simple , stalked or sessile, 2- to many forked , stellate , dendritic , or malpighiaceous (medifixed , bifid, appressed ), rarely peltate and scalelike; glandular trichomes multicellular, with uniseriate or multiseriate stalk . Stems erect , ascending , or prostrate , sometimes absent. Leaves exstipulate , simple, entire or variously pinnately dissected , rarely trifoliolate or pinnately, palmately, or bipinnately compound ; basal leaf rosette present or absent; cauline leaves almost always alternate, rarely opposite or whorled , petiolate or sessile, sometimes absent. Inflorescence bracteate or ebracteate racemes , corymbs, or panicles, sometimes flowers solitary on long pedicels originating from axils of rosette leaves . Flowers hypogynous, mostly actinomorphic . Sepals 4, in 2 decussate pairs, free or rarely united , not saccate or lateral (inner) pair saccate. Petals 4, alternate with sepals, arranged in the form of a cross (cruciform ; hence the earlier family name Cruciferae), rarely rudimentary or absent. Stamens 6, in 2 whorls, tetradynamous (lateral (outer) pair shorter than median (inner) 2 pairs), rarely equal or in 3 pairs of unequal length , sometimes stamens 2 or 4, very rarely 8-24; filaments slender, winged , or appendaged, median pairs free or rarely united; anthers dithecal , dehiscing by longitudinal slits. Pollen grains 3-colpate, trinucleate . Nectar glands receptacular , highly diversified in number, shape , size, and disposition around base of filaments, always present opposite bases of lateral filaments, median glands present or absent. Pistil 2-carpelled; ovary superior, sessile or borne on a distinct gynophore , mostly 2-locular and with a false septum connecting 2 placentae; placentation parietal , rarely apical; ovules anatropous or campylotropous, bitegmic, 1 to many per locule. Fruit typically a 2-valved capsule, generally termed silique (siliqua) when length 3 × or more than width , or silicle (silicula) when length less than 3 × width, dehiscent or indehiscent, sometimes schizocarpic, nutletlike, lomentaceous , or samaroid , segmented or not, terete , angled , or flattened parallel to septum (latiseptate ) or at a right angle to septum (angustiseptate) ; valves 2(or 3-6) ; replum (persistent placenta) rounded , rarely flattened or winged; septum complete, perforated, reduced to a rim , or lacking; style 1, distinct, obsolete , or absent; stigma capitate or conical , entire or 2-lobed, sometimes lobes decurrent and free or connate . Seeds without endosperm, uniseriately or biseriately arranged in each locule, aseriate when 1, winged or wingless, mucilaginous or not when wetted; cotyledons incumbent (embryo notorrhizal: radicle lying along back of 1 cotyledon), accumbent (embryo pleurorrhizal: radicle applied to margins of both cotyledons), or conduplicate (embryo orthoplocal: cotyledons folded longitudinally around radicle), rarely spirally coiled (embryo spirolobal) . Germination epigeal.

About 330 genera and 3500 species: all continents except Antarctica, mainly in temperate areas, with highest diversity in Irano-Turanian, Mediterranean, and W North American regions; 102 genera (eight endemic) and 412 species (115 endemic) in China.

Because of lack of a comprehensive classification based on phylogenetic relationships among genera, and in order to facilitate direct comparison between the accounts in FOC and FRPS, the sequence of genera follows Schulz (Nat. Pflanzenfam. 17b: 227-658. 1936) . However, it should be emphasized that his system is largely artificial because he placed closely related genera in different tribes and remotely related genera in the same tribe. For example, Arabis, Aubrieta, Draba, and Macropodium, which are very closely related on the basis of recent molecular studies, were placed by Schulz in four different tribes, whereas the unrelated Capsella, Lepidium, and Thlaspi were placed in one tribe. The delimitation of genera is often difficult, and mature fruits are needed for reliable identification.

The Brassicaceae include many important crop plants that are grown as vegetables (Brassica, Nasturtium, Raphanus) and sources of vegetable oils (Brassica) and condiments (Armoracia, Brassica, Eutrema, Sinapis) . Oils of Brassica probably rank first in terms of tonnage of the world's production of edible oils. The family includes many ornamentals in the genera Erysimum, Iberis Linnaeus, Lobularia, Malcolmia, and Matthiola. Of these, only Lobularia maritima has become naturalized in China. The family also includes more than 120 species of weeds . Arabidopsis thaliana, which is naturalized in China, has become the model organism in many fields of experimental biology .

The delimitation of genera in the Brassicaceae is often difficult because of the frequent independent evolution of what appear to be similar character states , the variability of a given character in one genus and its fixture in another, and the inadequate sampling of material by most authors . Fruit characters are essential in the identification of genera. However, a key emphasizing flowering material is given in addition to the one emphasizing fruit. The most reliable determination of genera can be achieved when the material has both fruit and flowers and when both keys are successfully used to reach the same genus.

The types of cotyledonary position, which in reality is the position of the radicle in relation to the cotyledons (e.g. , radicle accumbent, incumbent, or conduplicate, though radicle referred to as "cotyledon" throughout) are important in the separation of many genera, and a cross section of the seed provides the easiest and simplest way of determining that position. The exact number of ovules per ovary can easily be determined from the fruit because aborted ovules persist through fruit dehiscence. However, it is more laborious to determine the ovule number from pistils and young fruit.[1]

Subfamily Faboideae

Mostly herbs, shrubs , or trees . Leaves pinnate or palmate to trifoliolate or apparently simple . Corolla usually, showy, zygomorphic, the petals imbricate, posterior (upper or banner ) petal outermost in bud. Stamens 10 or 9 + 1 (diadelphous ), not showy. Pollen released in monads . Seeds with u-shaped line (pleurogram) lacking. [Carr]

Genus Draba

Herbs perennial , rarely annual , biennial (or subshrubs with woody stems). Trichomes simple , forked , stellate , malpighiaceous, or dendritic , stalked or sessile, often more than 1 kind present. Stems erect or ascending , sometimes prostrate , leafy or leafless and plants scapose . Basal leaves petiolate , often rosulate, simple, entire or toothed , rarely lobed . Cauline leaves petiolate or sessile, cuneate or auriculate at base , entire or dentate , sometimes absent. Racemes bracteate or ebracteate , elongated or not in fruit. Fruiting pedicels slender, erect, ascending, or divaricate . Sepals ovate , oblong , or elliptic , base of lateral pair not saccate or subsaccate, margin usually membranous. Petals yellow, white, pink, purple, orange (or rarely red) ; blade obovate , spatulate , oblong, oblanceolate , orbicular , or linear , apex obtuse , rounded , or rarely emarginate ; claw obscurely to strongly differentiated from blade. Stamens 6, tetradynamous ; filaments dilated or not at base; anthers ovate or oblong, obtuse at apex. Nectar glands 1, 2, or 4, distinct or confluent and subtending bases of all stamens; median glands present or absent; lateral glands toothlike, semiannular, or annular . Ovules 4 to numerous per ovary. Fruit dehiscent, silicles or rarely siliques, ovate, elliptic, oblong, orbicular, ovoid , globose , lanceolate, or linear, latiseptate or terete , sometimes spirally twisted; valves distinctly or obscurely veined, glabrous or pubescent ; replum rounded; septum complete , membranous, translucent ; style distinct or obsolete , glabrous; stigma capitate, entire or slightly 2-lobed. Seeds biseriate , wingless (or rarely winged ), oblong, ovate, or orbicular, flattened; seed coat minutely reticulate , not mucilaginous when wetted; cotyledons accumbent .

About 350 species: primarily in the N hemisphere, especially arctic , subarctic , alpine , and subalpine regions, with about 70 species in South America; 48 species (16 endemic) in China.

Draba is the largest and most taxonomically difficult genus in the Brassicaceae. More than 950 binomials and nearly a fourth as many infraspecific taxa have been proposed. Numerous taxa are based on trivial characters, especially the presence vs. absence of trichomes on the fruit valves. Otto Eugene Schulz (Pflanzenr. 89(IV . 105) : 1-396. 1927), hereafter Schulz (without a reference), was the last person to monograph Draba on worldwide basis. Although he accorded varietal names to forms with glabrous and pubescent fruits, this variation often occurs within the same population (see discussion under D. oreades). By contrast, petal color is taxonomically important and should be recorded in the field rather than from dried specimens because white petals sometimes dry yellow or vice versa. Another taxonomically important character is the number of ovules/seeds per ovary/fruit. This is easily obtained by counting the seeds and aborted ovules in the fruit.[2]

Physical Description

Habit: Forb/herb

Biology

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Reproduction

Duration: Perennial

Taxonomy

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Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 15-Mar-2000

Similar Species

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Members of the genus Draba

ZipcodeZoo has pages for 843 species, subspecies, varieties, forms, and cultivars in this genus. Here are just 100 of them:

D. acaulis · D. acinacis · D. affghanica · D. affinis · D. aizoidea · D. aizoides (Yellow Whitlow Grass) · D. aizoides 'Compacta' · D. aizoides subsp. beckeri · D. aizoides subsp. estevei · D. aizoon · D. ajanensis · D. alajica · D. alba · D. alberti · D. albertina (Slender Whitlow-Grass) · D. alchemilloides · D. aleutica (Aleutian Whitlow-Grass) · D. algida · D. allenii · D. alpestris · D. alpicola · D. alpina (Alpine Whitlow-Grass) · D. alpina f. longipedunculata · D. alpina f. oxycarpa · D. alpina var. bellii · D. alpina var. hydeana · D. alpina var. pilosa · D. altaica · D. althoa · D. alticola · D. alyssoides · D. ameghinoi · D. ameghiroi · D. americana · D. ammophila · D. amoena · D. amplexicaulis · D. andina · D. androsacea · D. apiculata · D. aprica (Open-Ground Whitlow-Grass) · D. arabis · D. arabisans (Rock Whitlow-Grass) · D. araboides · D. aradani · D. araratica · D. arauquensis · D. arbuscula · D. archibaldii · D. arctica (Arctic Whitlowgrass) · D. arctica groenlandica · D. arctica subsp. ostenfeldii (Ostenfeld's Whitlowgrass) · D. arctogena (Fell-Field Whitlow-Grass) · D. aretioides · D. aretioides f. subumbellata · D. argaea · D. argentea · D. argentina · D. argentina var. grandiflora · D. argyraea · D. argyrea (Western Whitlow-Grass) · D. argyrea var. glabrescens · D. arida (Desert Whitlow-Grass) · D. armata · D. armena · D. arsenievi · D. aspera · D. asperella · D. asprella (Rough Whitlow-Grass) · D. asprella Greene var. kaibabensis C.L.Hitchc. (Kaibab Whitlowgrass) · D. asprella Greene var. stelligera O.E.Schulz (Rough Whitlowgrass) · D. asprella var. asprella (Rough Whitlowgrass) · D. asprella var. kaibabensis (Kaibab Whitlowgrass) · D. asprella var. stelligera (Rough Whitlowgrass) · D. asprella var. zionensis (Zion Draba) · D. asprella Greene var. zionensis (C.L.Hitchc.) Welsh & Reveal (Zion Whitlow-Grass) · D. asterophora (Tahoe Whitlow-Grass) · D. asterophora Payson var. macrocarpa C.L.Hitchc. (Lake Tahoe Draba) · D. asterophora var. asterophora (Lake Tahoe Draba) · D. asterophora var. macrocarpa (Lake Tahoe Draba) · D. astyla · D. atacamensis · D. athoa · D. atlantica · D. atuelica · D. aubrietioides · D. aucheri · D. aurea (Golden Whitlowgrass) · D. aurea stylosa · D. aureiformis · D. aureiformis var. leiocarpa · D. aureola (Golden Alpine Draba) · D. australis · D. australis var. ameghinoi · D. austriaca · D. azoides · D. azorellicola · D. bagmatiensis · D. baicalensis · D. balangshanica

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 19, 2007:

Identifiers

Footnotes

  1. Tai-yien Cheo, Lianli Lu, Guang Yang, Ihsan Al-Shehbaz & Vladimir Dorofeev "Brassicaceae". in Flora of China Vol. 8 Page 1. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  2. "Draba". in Flora of China Vol. 8 Page 66. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
Last Revised: 7/1/2009