Desmodium

Desmodium is a genus in the flowering plant family Fabaceae, sometimes called tick-trefoil, tick clover, hitch hikers or beggar lice. There are dozens of species and the delimitation of the genus has shifted much over time.

Desmodium
Desmodium heterocarpon
Scientific classification
Kingdom:
Plantae
(unranked):
Angiosperms
(unranked):
Eudicots
(unranked):
Rosids
Order:
Fabales
Family:
Fabaceae
Subfamily:
Faboideae
Tribe:
Desmodieae
Subtribe:
Desmodiinae
Genus:
Desmodium

Species

Many, see text

Synonyms
  • Catenaria Benth.
  • Desmofischera Holthuis
  • Desmodium DC.
  • Dollinera Endl.
  • Grona Lour.
  • Hanslia Schindl.
  • Hegnera Schindl.
  • Holtzea Schindl.
  • Hylodesmum H. Ohashi & R. R. Mill
  • Meibomia Heist. ex Fabr.
  • Monarthrocarpus Merr.
  • Murtonia Craib
  • Nephromeria (Benth.) Schindl.
  • Nicolsonia DC.
  • Ohwia H. Ohashi
  • Ougeinia Benth.
  • Papilionopsis Steenis
  • Pleurolobus J. St.-Hil.
  • Podocarpium (Benth.) Y. C. Yang & P. H. Huang

These are mostly inconspicuous legumes; few have bright or large flowers. Though some can become sizeable plants, most are herbs or small shrubs. Their fruit are loments, meaning each seed is dispersed individually enclosed in its segment. This makes them tenacious plants and some species are considered weeds in places. They have a variety of uses, as well.

Uses
Desmodium intortum
Desmodium triflorum

Several Desmodium species contain potent secondary metabolites that are released into the soil and aerially. Allelopathic compounds are used aggressively in agriculture in push-pull technology: Desmodium heterocarpon, Desmodium intortum, and Desmodium uncinatum are inter-cropped in maize and sorghum fields to repel Chilo partellus, a stem-boring grass moth, and suppress witchweeds, including Asiatic witchweed (Striga asiatica) and purple witchweed (S. hermonthica).[1] High amounts of antixenotic allomones produced by Desmodium also repel insect pests. Different Desmodium species produce different profiles of organic compounds through their root systems. The reasons for the production of these compounds that have benefited cereal crop production are however unknown, as they don't seem to serve any apparent function to the plant itself.

Tick-trefoils are also useful as living mulch and as green manure, as they are able to improve soil fertility via nitrogen fixation. Most also make good fodder for animals including bobwhite, turkey, grouse, deer, cattle and goats.[1][2][3]

Some Desmodium species have been shown to contain high amounts of tryptamine alkaloids, though many tryptamine-containing Desmodium species have been transferred to other genera.[1]

The caterpillars of the lesser grass blue (Zizina otis) and the two-barred flasher (Astraptes fulgerator) feed on tick-trefoils. Deer also appear to rely on some species in certain areas, particularly during the more stressful summer months.

Taxonomy and systematics
Beggar lice seeds readily stick to many objects, such as this shoe

The taxonomy and systematics of the many dozens of Desmodium species are confusing and unresolved. Related genera such as Codariocalyx, Hylodesmum, Lespedeza, Ohwia, and Phyllodium were and sometimes still are included in Desmodium.[4]

Taxonomic authorities commonly disagree about the naming and placement of species. For example, Desmodium spirale as described by August Grisebach might refer to a distinct species, but its validity is doubtful. The "Desmodium spirale" of other authorities may refer to D. neomexicanum, D. ospriostreblum, or D. procumbens. Similarly, the plant originally described as D. podocarpum by A. P. de Candolle is Hylodesmum podocarpum today, but "Desmodium podocarpum" might also refer to D. hookerianum or Hylodesmum laxum, depending on the taxonomic authority.[4]

Selected species
Main article: List of Desmodium species

Species include:[5][4][6]

Desmodium oojeinense, Dietrich Brandis (1874): Illustrations of the Forest Flora of North-West and Central India.
  • Desmodium acanthocladum F.Muell.
  • Desmodium canadense (L.) DC. – showy tick-trefoil, Canadian tick-trefoil
  • Desmodium canescens (L.) DC. – hoary tick-trefoil
  • Desmodium ciliare (Muhl.) DC. – hairy small-leaved tick-trefoil
  • Desmodium cuspidatum (Muhl.) Loudon – toothed tick-trefoil, large-bracted tick-trefoil
  • Desmodium glabellum (Michx.) DC.
  • Desmodium heterocarpon (Michx.) DC. – Asian tick-trefoil
  • Desmodium × humifusum (Muhl. ex Bigelow) Beck
  • Desmodium illinoense A.Gray – Illinois tick-trefoil
  • Desmodium incanum (Sw.) DC. – creeping beggarweed, Spanish tick-trefoil, Kaimi clover
  • Desmodium lineatum (Michx.) DC. – linear-leaved tick-trefoil
  • Desmodium marilandicum (L.) DC. – smooth small-leaved tick-trefoil
  • Desmodium ospriostreblum Chiov.
  • Desmodium paniculatum (L.) DC. – panicled tick-trefoil
  • Desmodium perplexum B.G.Schub. – perplexed tick-trefoil
  • Desmodium rhytidophyllum F.Muell. ex Benth.
  • Desmodium rotundifolium DC. – round-leaved tick-trefoil, dollar leaf
  • Desmodium triflorum (L.) DC.
  • Desmodium tweedyi Britton – Tweedy's tick-trefoil
  • Desmodium uncinatum (Jacq.) DC.– silver-leaved tick-trefoil, silverleaf
  • Desmodium varians (Labill.) G.Don

Formerly placed here[4]
  • Codariocalyx motorius – telegraph plant (as D. gyrans, D. motorium, D. roylei)
  • Hylodesmum laxum (as D. laxum DC.)
    Lespedeza thunbergii was formerly known as Desmodium formosum and Desmodium thunbergii
    • Hylodesmum laxum ssp. laxum (as D. austro-japonense, D. bambusetorum, D. gardneri auct. non Benth., D. laxiflorum sensu Miq., D. laxum var. kiusianum, D. laxum ssp. laxum, D. podocarpum auct. non DC. non Hook. & Arn., D. podocarpum DC. var. gardneri sensu Bedd., D. podocarpum DC. var. laxum)
  • Hylodesmum leptopus (as D. gardneri Benth., D. laxum auct. non DC., D. laxum ssp. leptopus, D. leptopus, D. tashiroi)
  • Hylodesmum podocarpum (as D. podocarpum DC., D. podocarpum DC. var. indicum, D. podocarpum DC. var. japonicum)
    • Hylodesmum podocarpum ssp. oxyphyllum (as D. fallax var. mandshuricum, D. japonicum, D. mandshuricum, D. oxyphyllum DC., D. podocarpum DC. var. mandshuricum, D. podocarpum DC. ssp./var. oxyphyllum, D. podocarpum DC. var. polyphyllum, D. podocarpum DC. var. typicum, D. racemosum)
  • Lespedeza thunbergii (as D. formosum, D. thunbergii)
    • Lespedeza thunbergii var. thunbergii (as D. penduliflorum Oudem.)
  • Ohwia caudata (as D. caudatum)
  • Phyllodium pulchellum (as D. pulchellum)
  • Dendrolobium umbellatum (as D. umbellatum (L.) Benth.
  • Dendrolobium triangulare (as D. Desmodium umbellatum Moritz.

References
  • International Legume Database & Information Service (ILDIS) (2005): Genus Desmodium. Version 10.01, November 2005. Retrieved 2007-DEC-17.
  1. "The Plant Encyclopedia - Desmodium". The Plant Encyclopedia. Retrieved 17 January 2014.
  2. "Plants Profile for Desmodium (ticktrefoil)". plants.usda.gov.
  3. "Know Your Deer Plants: Beggar's Lice - Quality Deer Management Association". 25 January 2012.
  4. ILDIS (2005)
  5. "Desmodium Desv". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 20 January 2020.
  6. Pires Lima LC, de Queiroz LP, de Azevedo Tozzi AMG, Lewis GP (2014). "A Taxonomic Revision of Desmodium (Leguminosae, Papilionoideae) in Brazil". Phytotaxa. 169 (1): 1–119. doi:10.11646/phytotaxa.169.1.1.
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