Domesticating horsegram

The indefatigable Dorian Fuller has been even less fatigable than usual lately, with a couple of papers in the past few weeks on the history of the horsegram, Macrotyloma uniflorum. The first is a general review of the geographical, linguistic and archaeological evidence for the origins of the crop. They point to a long history in India and at least two separate domestications there.

Fig. 7. Map of distribution of wild populations of horsegram based upon data from Table 5 (and Table S4), and including M. sar-garhwalensis.

The second is a much deeper dive into the history of domestication, using high resolution x-ray computed tomography with a synchrotron to measure non-destructively the decrease in seed coat thickness with time in archaeological remains of domesticated material. A thin seed coat is thought to be related to loss of dormancy, and hence part of the domestication syndrome. It had been suggested that rare non-dormant variants might have been selected during domestication, but the evidence from horsegram is that even the thick-coated, and therefore presumably still dormant, material was domesticated.

Which is all very interesting, but what I want to leave you with is a little quiz. Given that Kersting’s groundnut is now also in Macrotyloma, as M. geocarpum (Harms) Maréchal & Baudet, how many other con-generic species can you think of that were domesticated on separate continents? Apart from the two Oryza species, of course.

8 Replies to “Domesticating horsegram”

  1. Many multi-continent millets!
    Digitaria cricuiata (domesticated around Assam); Digitaria exilis and Digitaria iburua (west Africa)
    Brachiaria ramosa (India); Brachiaria deflexa (West Africa)
    Panicum miliaceum (China); Panicum sumatrense (India); Panicum sonorum (American Southwest)
    Setaria italica (China); Setaria pumila and Setaria verticilata (India); Setaria macrostachya and Setaria parviflora (Mexico); Setaria sphacelata (Nubia/Africa, but now extinct in cultivation[?]), Setaria palmifolia (New Guinea, but grown for green vegetative parts, not grain)

    Also Vigna spp:
    Vignua unguiculata and Vigna subterannea (Africa)
    Vigna radiata, V. mungo, V. aconitifolia (India)
    V. umbellata (SE Asia)
    V. angularis (Japan)

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