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Digitaria violascens

(Violet Crabgrass)

Overview

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Interesting Facts

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Common Names

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Click on the language to view common names.

Common Names in Chinese:

Zi Ma Tang

Common Names in English:

Violet Crabgrass, Purple Crabgrass

Common Names in Japanese:

Akime Hishiba

Description

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Genus Digitaria

Annual or perennial . Culms erect or decumbent , occasionally stoloniferous . Leaf blades linear or linear-lanceolate; ligule membranous. Inflorescence of digitately arranged racemes , sometimes on a short axis or with secondary branchlets , very rarely paniculate ; spikelets usually in groups of 2-3(-4), imbricate to effuse, the latter often on notably long and unequal pedicels. Spikelets puberulous to villous , typically in stripes between the well-defined veins, rarely glabrous ; lower glume absent or reduced to a little scale up to 1/4 spikelet length; upper glume variable; lower lemma usually ± equal to spikelet; upper floret pallid to black, apex subacute to acuminate, rarely apiculate . x = 9.

About 250 species:tropical and warm-temperate regions of the world; 22 species (three endemic) in China.

Digitaria has been traditionally divided on the nature of the spikelet hairs, which may be clavate , capitate, verrucose (warty, appearing beaded), or with crooked tips . As good magnification is required to see these features, the grouping of the spikelets on the raceme is a more practical aid to identification. Many species have regularly paired spikelets, which present no difficulty. In those species where the spikelets are grouped in clusters of 3 or more, care must be taken, as often the longest pedicel of a group is partially fused to the rachis so that the spikelets appear alternately paired and single, or sometimes one spikelet may be vestigial, or the spikelets may be paired toward the raceme tips.

Many species are very variable in spikelet pubescence and lemma nervation, even within a single raceme. Additionally, there are a number of complexes of intergrading species, so intermediates may occasionally be encountered. This has led to the publication of many superfluous names .[1]

Physical Description

Species Digitaria violascens

Annual . Culms loosely tufted , infrequently shortly stoloniferous , 20-60 cm tall. Leaf sheaths glabrous or pilose , especially at mouth ; leaf blades linear-lanceolate, 5-15 × 0.2-0.6 cm, scabrous , glabrous or adaxial surface pilose at base , apex acute; ligule 1-2 mm. Inflorescence subdigitate; racemes (2-) 3-7(-10), ascending , 3-12 cm; spikelets ternate ; rachis ribbonlike, winged , 0.5-0.8 mm broad, midrib low and rounded , margins serrate; pedicels angular, scabrous, with discoid tips . Spikelets elliptic-oblong, 1.4-1.9(-2.5) mm, hairs verrucose , sometimes hook-tipped; lower glume absent; upper glume lanceolate, slightly shorter than spikelet, 3(-5) -veined, intervein spaces and margins appressed-pubescent; lower lemma as long as spikelet, 5-7-veined, intervein spaces and margins pubescent , but usually glabrous flanking the middle vein ; upper lemma dark brown or purplish black at maturity. Anthers 0.3-0.6 mm. Fl. and fr. Jul-Nov. 2n = 36. [source]

This widespread, weedy species is closely related to Digitaria longiflora, and there is some overlap between the two. Digitaria violas-cens tends to be tufted rather than stoloniferous, with 3 or more longer racemes, angular, scabrous pedicels, a shorter, 3-veined upper glume, and distinctive, blackish fruits. [source]

Habit: Graminoid

Habitat

Hillsides, roadsides, weedy places; ca. 1000 m. [2].

Biology

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Reproduction

Duration: Annual , Perennial

Growth

Temperature: Cold Hardiness: 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b, 11. (map)

Taxonomy

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Synonyms

D. pertenuis Buse • D. thwaitesii (Hackel) Henrard Var. tonkinensis Henrard • D. violascens (Link) Var. villosa Keng • Digitaria chinensis (Nees) A. Camus (1923) • Digitaria ischaemum (Schreb.) Schreb. Ex Muhl. Var. violascens (Link) Radford • Digitaria ischaemum var. violascens (Link) Radford • Digitaria Ischaemum Violascens • Digitaria ischaemum violascens (Link) Radford • Digitaria Violascens • P. minutiflorum Steudel (1853) • P. violascens (Link) Kunth • Panicum steudelianum Domin • Panicum violascens (Link) Kunth • Paspalum chinense Nees • Syntherisma chinensis (Nees) A. S. Hitchc. • Syntherisma chinensis (Nees) Hitchcock.

Notes

Name Status: Accepted Name .

Last scrutiny: 15-Mar-2000

Similar Species

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Members of the genus Digitaria

ZipcodeZoo has pages for 53 species, subspecies, varieties, forms, and cultivars in this genus:

D. abyssinica (African Couchgrass) · D. arenicola (Fall Witchgrass) · D. argillacea (Tropical Crabgrass) · D. bicornis (Asia Crabgrass) · D. californica (Arizona Cottontop) · D. ciliaris (Fingergrass) · D. cognata (Carolina Cottontop) · D. cognata var. cognata (Carolina Crabgrass) · D. cognata var. pubiflora (Carolina Crabgrass) · D. cruciata (Crabgrass) · D. diagonalis (Brown-Seeded Finger Grass) · D. didactyla (Crabgrass) · D. dolichophylla (Caribbean Crabgrass) · D. eggersii (Eggers' Crabgrass) · D. eriantha (Pangola Grass) · D. eriantha subsp. eriantha (Crabgrass) · D. eriantha subsp. pentzii (Woolly Fingergrass) · D. exilis (Fonio) · D. filiformis (Slender Crabgrass) · D. floridana (Florida Crabgrass) · D. fuscescens (Yellow Crabgrass) · D. gracillima (Long-Leaf Crabgrass) · D. henryi (Henry´s Crabgrass) · D. hitchcockii (Short-Leaf Crabgrass) · D. horizontalis (Jamaica Crabgrass) · D. iburua (Black Fonio) · D. insularis (Sourgrass) · D. ischaemum (Small Crabgrass) · D. ischaemum var. ischaemum (Small Crabgrass) · D. longiflora (India Crabgrass) · D. milanjiana (Madagascar Crabgrass) · D. natalensis (Natal Crabgrass) · D. nuda (Naked Crabgrass) · D. panicea (Millet Crabgrass) · D. patens (Texas Cottontop) · D. pauciflora (Florida Pineland Crabgrass) · D. pubiflora (Carolina Crabgrass) · D. radicosa (Trailing Crabgrass) · D. sanguinalis (Crabgrass) · D. seriata (Crabgrass) · D. serotina (Blanket Crabgrass) · D. setigera (East Indian Crabgrass) · D. setivalva (Crabgrass) · D. similis (Roadside Crabgrass) · D. simpsonii (Isle-Of-Pines Crabgrass) · D. swalleniana (Swallen's Crabgrass) · D. ternata (Black-Seeded Crabgrass) · D. texana (Texas Crabgrass) · D. tomentosa (Woolly Crabgrass) · D. umfolozi (Crabgrass) · D. velutina (Annual Couchgrass) · D. villosa (Shaggy Crabgrass) · D. violascens (Violet Crabgrass)

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 13, 2007:

Identifiers

Footnotes

  1. Shou-liang Chen & Sylvia M. Phillips "Digitaria". in Flora of China Vol. 22 Page 1, 500, 539. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  2. "Digitaria violascens". in Flora of China Vol. 22 Page 541, 546, 547. Missouri Botanical Garden Press. Online at EFloras.org. [back]
Last Revised: 7/15/2012