17.27   ELEUSINE Gaertn.
Khidir W. Hilu

Plants annual or perennial; cespitose. Culms 10-150 cm, herbaceous, glabrous, branching both at and above the base. Sheaths open; ligules membranous, ciliate. Inflorescences terminal, panicles of (1)2-20 non-disarticulating, spikelike branches, exceeding the upper leaves; branches 1-17 cm, all or most in a digitate cluster, sometimes 1(2) branch(es) attached immediately below the terminal whorl, axes flattened, terminating in a functional spikelet. Spikelets 3.5-11 mm, laterally compressed, with 2-15 bisexual florets; disarticulation above the glumes and between the florets (Eleusine coracana not disarticulating). Glumes unequal, shorter than the lower lemmas; lower glumes 1-3-veined; upper glumes 3-5(7)-veined; lemmas 3-veined, glabrous, keeled, apices entire, neither mucronate nor awned; paleas sometimes with winged keels; anthers 3, 0.5-1 mm; ovaries glabrous. Fruits modified caryopses, pericarp thin, separating from the seed at an early stage in its development; seeds usually obtusely trigonous, the surfaces ornamented. x = 8, 9, 10. Name from Eleusis, a Greek town where Demeter, the goddess of harvests, was worshipped.

Eight of the nine species of Eleusine are native to Africa, where they grow in mesic to xeric habitats; the exception, E. tristachya, is native to South America. Three species have become established in the Flora region. When moistened, the seeds of all species are easily freed from the thin pericarp.

Eleusine coracana subsp. africana, E. indica, and E. tristachya are widely distributed weeds. Eleusine coracana subsp. coracana was domesticated in East Africa and subsequently introduced to India and China. It is frequently grown for grain in India and Africa.


SELECTED REFERENCES Hilu, K.W.1980. Noteworthy collections: Eleusine tristachya. Madroño 27:177-178; Hilu, K.W. and J.L. Johnson. 1997. Systematics of Eleusine Gaertn. (Poaceae, Chloridoideae): Chloroplast DNA and total evidence. Ann. Missouri Bot. Gard. 84:841-847; Phillips, S.M. 1972. A survey of the genus Eleusine Gaertner (Gramineae) in Africa. Kew Bull. 27:251-70.

1
Panicles with 1-3 oblong branches 1-6(8) cm long, attached in a single digitate cluster ..... 3. E. tristachya
Panicles with 4-20 linear branches 3.5-17 cm long, 1(2) of the branches attached below the terminal, digitate cluster (2)
2
Lower glumes 1-veined; panicle branches 3-5.5 mm wide; surface of the seeds striate ..... 1. E. indica
Lower glumes 2- or 3-veined; panicle branches 5-15 mm wide; surface of the seeds granular ..... 2. E. coracana


1.   Eleusine indica (L.) Gaertn.
Goosegrass, Eleusine d'Inde

Plants annual. Culms 30-90 cm, erect or ascending, somewhat compressed; lower internodes 1.5-2 mm thick. Sheaths conspicuously keeled, margins often with long, papillose-based hairs, particularly near the throat; ligules 0.2-1 mm, truncate, erose; blades 15-40 cm long, 3-7 mm wide, with prominent, white midveins, margins and/or adaxial surfaces often with basal papillose-based hairs. Panicles with 4-10(17) branches, often with 1 branch attached as much as 3 cm below the terminal cluster; branches (3.5)7-16 cm long, 3-5.5 mm wide, linear. Spikelets 4-7 mm long, 2-3 mm wide, with 5-7 florets, obliquely attached to the branch axes. Lower glumes 1.1-2.3 mm, 1-veined; upper glumes 2-2.9 mm; lemmas 2.4-4 mm; paleas with narrowly winged keels. Seeds ovoid, rugulose and obliquely striate, usually not exposed at maturity. 2n = 18.

Eleusine indica is a common weed in the warmer regions of the world. In the Flora region, it usually grows in disturbed areas and lawns, and has been found in most states of the contiguous United States.


2.   Eleusine coracana (L.) Gaertn.

Plants annual. Culms to 62 cm, often branching; lower internodes 6-10 mm thick. Sheaths glabrous; ligules 1-2 mm, ciliate, with 1-2 mm hairs; blades 10-60 cm long, 6-12 mm wide, sometimes longer than the culms, adaxial surfaces scabrous or pubescent. Panicles subdigitate, with 4-20 branches, 1(2) of the branches attached below the terminal cluster; branches 4-17 cm long, 5-15 mm wide, spreading at maturity. Spikelets 5-9 mm long, 3-6 mm wide, with 2-9 florets, sometimes not disarticulating at maturity. Lower glumes 1.2-3 mm, 2- or 3-veined; upper glumes 2.2-6.5 mm; lemmas 2.2-5 mm; anthers about 1 mm. Seeds oblong-globose, granular, usually exposed at maturity. 2n = 36.

Eleusine coracana is an allotetraploid, one of its genomes being derived from E. indica. Two subspecies are recognized; only subsp. coracana is known from North America.

1
Seeds almost globose, the surface granular to smooth; florets not disarticulating ..... subsp. coracana
Seeds oblong, the surface shallowly ridged and uniformly granular; florets disarticulating at maturity ..... subsp. africana


Eleusine coracana subsp. africana (Kenn.-O'Byrne) Hilu & de Wet
African Finger Millet, Finger Millet

Culms 21-62 cm. Blades 22-50 cm long, 6-10 mm wide. Branches slim, 4-17 cm long, 5-7 mm wide. Spikelets 5-8 mm long, 3-4 mm wide, with 2-6 florets, disarticulating at maturity. Seeds oblong, surfaces shallowly ridged, uniformly granular.

This weedy subspecies hybridizes freely with the cultivated subsp. coracana. It tends to have more slender branches than subsp. coracana (5-7 mm wide rather than 7-15 mm), which led to its previous inclusion in E. indica.


Eleusine coracana (L.) Gaertn. subsp. coracana
Finger Millet, Ragi

Culms to 17 cm. Blades 30-60 cm long, 6-12 mm wide. Branches 4-14 cm long, 7-15 mm wide, spikelets closely imbricate. Spikelets 5-9 mm long, brown, with 6-9 florets, florets not disarticulating at maturity. Seeds almost globose, brownish, surfaces granular to smooth.

Eleusine coracana subsp. coracana is the domesticated variant of E. coracana. Biochemical data suggest that it evolved from a few populations of the very variable subsp. africana. It is cultivated at various agricultural experiment stations and occasionally escapes.

Eleusine coracana subsp. coracana has a long historical record dating back at least 5000 years in Africa, and 3000 years in India. Five races, based on inflorescence morphology, are recognized in East Africa where it is widely cultivated for food and drink.


3.   Eleusine tristachya (Lam.) Lam.
Threespike Goosegrass

Plants annual. Culms 10-45 cm, compressed. Blades 6-25 cm long. Panicles digitate, with (1)2-3 branches; branches 1-6(8) cm long, 5-14 mm wide, oblong. Spikelets 8-10 mm, with 5-9(11) florets. Glumes unequal; lower glumes 2-3 mm; upper glumes 3-4 mm; lemmas 4-5 mm. 2n = 18.

Eleusine tristachya was originally thought to be native to tropical Africa and introduced into tropical America, but it occurs in Africa only as a rare adventive. It is now considered to be native to tropical America. In the 1800s and early 1900s, it was found on ballast dumps at various ports and transportation centers in the United States. More recently, it has been found as a weed in the Imperial Valley of California (Hilu 1980). All records of collections outside of California appear to be historical, with no populations persisting. That from Texas, for instance, was made from a plant growing in a range management area associated with one of the Texas A&M University farms. Although not deliberately cultivated, it probably was an escape. The species has not been collected since in Texas.