Medicago


Medicago is a genus of flowering plants, commonly known as medick or burclover, in the legume family. It contains at least 87 species and is distributed mainly around the Mediterranean Basin, and extending across temperate Eurasia and sub-Saharan Africa. The best-known member of the genus is alfalfa, an important forage crop, and the genus name is based on the Latin name for that plant, medica, from Median. Most members of the genus are low, creeping herbs, resembling clover, but with burs. However, alfalfa grows to a height of 1 meter, and tree medick is a shrub. Members of the genus are known to produce bioactive compounds such as medicarpin and medicagenic acid. Chromosome numbers in Medicago range from 2n = 14 to 48.
The species Medicago truncatula is a model legume due to its relatively small stature, small genome, short generation time, and ability to reproduce both by outcrossing and selfing.
Comprehensive descriptions of the genus are Lesinš and Lesinš 1979 and Small and Jomphe 1989. Major collections are SARDI, USDA-GRIN, ICARDA, and INRA.

Evolution

Medicago diverged from Glycine about 53–55 million years ago, from Lotus 49–51 million years ago, and from Trigonella 10–22 million years ago.

Ecological interactions with other organisms

Symbiosis with nitrogen-fixing rhizobia

Béna et al. constructed a molecular phylogeny of 23 Sinorhizobium strains and tested the symbiotic ability of six strains with 35 Medicago species. Comparison of these phylogenies indicates many transitions in the compatibility of the association over evolutionary time. Furthermore, they propose that the geographical distribution of strains limits the distribution of particular Medicago species.

Agricultural uses

Agronomic research has been conducted on species of the Medicago genus. Other than alfalfa, several of the prostrate members of the family have been used as forage crops. Select species in the Medicago genus naturally develop spiney pods during the reproductive phase of growth. Despite having high levels of agronomic performance, these are typically viewed as undesirable in sheep based farming systems due to their ability to become lodged in wool, reducing fleece value. Breeding efforts in the 1990's have yielded spineless varieties of burr medic, providing valuable production amongst farming systems in low rainfall, free draining, alkaline soils.

Insect herbivores

Medicago species are used as food plants by the larvae of some Lepidoptera species including the common swift, flame, latticed heath, lime-speck pug, nutmeg, setaceous Hebrew character, and turnip moths and case-bearers of the genus Coleophora, including C. frischella and C. fuscociliella.

Species

This list is compiled from:

Section Buceras

Subsection Deflexae

Medicago retrorsa E. Small

Subsection Erectae

Medicago arenicola E. SmallMedicago astroites Trautv.Medicago carica E. SmallMedicago crassipes E. SmallMedicago fischeriana Trautv.Medicago halophila E. SmallMedicago heldreichii E. SmallMedicago medicaginoides E. SmallMedicago monantha Trautv.Medicago orthoceras Trautv.Medicago pamphylica E. SmallMedicago persica E. SmallMedicago phrygia E. SmallMedicago polyceratia Trautv.Medicago rigida E. Small

Subsection Isthmocarpae

Medicago rhytidiocarpa E. SmallMedicago isthmocarpa E. Small

Subsection Reflexae

Medicago monspeliaca Trautv.

Section Carstiensae

Medicago carstiensis Wulf.

Section Dendrotelis

Medicago arborea L.Medicago citrina GreuterMedicago strasseri Greuter, Matthas & Risse

Section Geocarpa

Medicago hypogaea E. Small

Section Heynianae

Medicago heyniana Greuter

Section Hymenocarpos

Medicago radiata L.

Section Lunatae

Medicago biflora E. SmallMedicago brachycarpa M. Bieb.Medicago huberi E. SmallMedicago rostrata E. Small

Section Lupularia

Medicago lupulina L.Medicago secundiflora Durieu

Section Medicago

Medicago cancellata M. Bieb.Medicago daghestanica Rupr.Medicago hybrida Trautv.Medicago marina L.Medicago papillosa Boiss.
  • * M. p. macrocarpa
  • * M. p. papillosaMedicago pironae Vis.Medicago prostrata Jacq.
  • * M. p. prostrata
  • * M. p. pseudorupestrisMedicago rhodopea Velen.Medicago rupestris M. BiebMedicago sativa L.
  • * M. s. caerulea
  • * M. s. falcata
  • ** M. s. f. var. falcata
  • ** M. s. f. var. viscosa
  • * M. s. glomerata
  • * M. s. sativaMedicago saxatilis M. BiebMedicago suffruticosa Ramond ex DC.
  • *M. s. leiocarpa
  • *''M. s. suffruticosa''

Section Orbiculares

Medicago orbicularis Bart.

Section Platycarpae

Medicago archiducis-nicolai SirjaevMedicago cretacea M. Bieb.Medicago edgeworthii SirjaevMedicago ovalis SirjaevMedicago playtcarpa Trautv.Medicago plicata SirjaevMedicago popovii SirjaevMedicago ruthenica Ledebour

Subsection Rotatae

Medicago blancheana Boiss.Medicago noeana Boiss.Medicago rugosa Desr.Medicago rotata Boiss.Medicago scutellata MillerMedicago shepardii Post

Section Spirocarpos

Subsection Intertextae

Medicago ciliaris KrockerMedicago granadensis Willd.Medicago intertexta MillerMedicago muricoleptis Tin.

Subsection Leptospireae

Medicago arabica Huds.Medicago coronata Bart.Medicago disciformis DC.Medicago laciniata MillerMedicago lanigera Winkl. & Fedtsch.Medicago laxispira HeynMedicago minima Bart.Medicago polymorpha L.Medicago praecox DC.Medicago sauvagei NègreMedicago tenoreana Ser.

Subsection Pachyspireae

Medicago constricta DurieuMedicago doliata Carmign.Medicago italica FioriMedicago lesinsii E. SmallMedicago littoralis Rohde ex Lois.Medicago murex Willd.Medicago rigidula All.Medicago rigiduloides E. SmallMedicago sinskiae UljanovaMedicago soleirolii DubyMedicago sphaerocarpos Bertol.Medicago syriaca E. SmallMedicago truncatula Gaertn.Medicago turbinata All.

Species names with uncertain taxonomic status

The status of the following species is unresolved:Medicago agropyretorum Vassilcz.Medicago alatavica Vassilcz.Medicago caucasica Vassilcz.Medicago cyrenaea Maire & WeillerMedicago difalcata SinskayaMedicago grossheimii Vassilcz.Medicago gunibica Vassilcz.Medicago hemicoerulea SinskayaMedicago karatschaica A. HellerMedicago komarovii Vassilcz.Medicago meyeri GrunerMedicago polychroa Grossh.Medicago schischkinii Sumnev.Medicago talyschensis Latsch.Medicago transoxana Vassilcz.Medicago tunetana A.W. HillMedicago vardanis Vassilcz.Medicago virescens Grossh.
Recent molecular phylogenic analyses of Medicago indicate that the sections and subsections defined by Small & Jomphe, as outlined above, are generally polyphyletic. However, with minor revisions sections and subsections could be rendered monophyletic.