All Floras      Search Specimen
Login | eFloras Home | Help
IBSC | Family List | Cruciferae

Draba Linn.

葶苈属

Description from Flora of China

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.

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.

The records from China of Draba fladnizensis Wulfen (e.g., FRPS, p. 160; Fl. Qinghai. 1: 443. 1997; Fl. Xinjiang. 2(2): 117. 1995) and D. hirta Linnaeus (e.g., FRPS, p. 164; Fl. Xinjiang. 2(2): 127. 1995) cannot be confirmed, and it is likely that these records are based on 19th Century accounts that represent misidentifications of plants of several species, including D. altaica, D. lanceolata, D. lasiophylla, D. mongolica, and D. oreades.

Draba affghanica Boissier was recorded from Gansu by Pohle (Repert. Spec. Nov. Regni Veg. Beih. 32: 128. 1925), but the present authors have seen no Chinese material of that species.

According to FRPS (p. 168), Fl. Qinghai. (1: 449. 1997), and Fl. Xinjiang. (2(2): 125. 1995), Draba borealis de Candolle was said to occur in Qinghai, Shaanxi, Sichuan, and Xinjiang. However, the present authors have seen no material from these provinces. The distribution of D. borealis in Asia is restricted to Russia (only the coastal Far East, not Siberia) and Japan. It is highly unlikely that the species occurs in China.

Draba fuhaiensis Z. X. An (Fl. Xinjiang. (2(2): 374. 1995) is not included in the present account because the present authors have not seen the type, which was the single collection cited.

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.


 

Related Objects  

Flora of Chile  
  • PDF
  • PDF
    Flora of China  
  • Publication
  • PDF
  • PDF File
  • PDF
    Photos by The Biodiversity of the Hengduan Mountains Project  
  • Image File (SUN Hang)
  • Image/JPEG

    IBSC @ efloras.org
    Browse by
    Family
    Genera
    Search by name

    Specimen Search

    People @ IBSC

     

     

     |  eFlora Home |  People Search  |  Help  |  ActKey  |  Hu Cards  |  Glossary  |