Digitate means "finger-like" and a digitate inflorescence is one in which several racemes or spikes come from, or at least appear to come from, a common point at the top of a culm, somewhat like fingers (digits) on a hand. The number of spikes or racemes is given in the key as (for example): (1-)3-9, where the number in parentheses represents the uncommon extreme(s), and the count represents the typical range for that species. In some of these grasses, there may be one or more racemes or spikes located below the more crowded grouping forming the fingers of the flower head. In our digitate inflorescences the spikelets are tightly arranged in two rows along only one side of the rachis, an arrangement termed secund or unilateral.

Our most common grasses with spikes or racemes arranged digitately are:

Swollen fingergrass [46a] —extremely common medium size grass of roadsides and waste areas; other Chloris spp. are common and can be locally abundant.

Wiregrass [44a]—small, coarse weed grass widespread in lawns and disturbed places.  

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Figure 12A. Digitate flowering head
of Rhodes grass (Chloris gayana).

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[DIGITATE INFLORESCENCE]

Inflorescence an umbrella like arrangement of (1-)3-9 spikes. Each spike with two rows of downward-pointing bristled spikelets appearing like teeth on a comb. Rachis usually extending as a conspicuous point beyond last spikelets. Ligule a fimbriate membrane. { Widespread although typically not abundant where found; small running grass (Fig. 12B). Beach wiregrass [HAW - NAT] crowfoot grass [GUM - NAT]

   Dactyloctenium aegyptium (L.) Willd.

Inflorescence of spikes or racemes, with or without bristles, but not comb-like in appearance, the spikelets tending to lay flat against the rachis, the tip of which is hidden by uppermost spikelets .. .

Inflorescence of 3 to 9 delicate, narrow spikes or racemes. Small grass spreading by stolons or rhizomes or both .. .

Coarse, medium, spreading grass. Spikelets 3 mm or less in length. Ligule a dense fringe of hairs .. .

Eleusine indica (L.) Gaertn.

Inflorescence of (5-)7-20 spikes. Spikelets with several short awns, the longest about as long again as a spikelet, the shortest very short and on the upper glume; some bractioles ciliate. { Medium perennial grass of open, disturbed areas, verges, and pastures (Fig. 12A). (See also couplet [48a]) Rhodes grass [HAW - NAT] [FACU] [GUM - NAT]

Chloris gayana Kunth

Spikelets ovate, broadly or not, but without awns. Leaf arrangement alternate or distichous (two-ranked; alternating blades coming off culm in two vertical rows on opposite sides of the axis) .. .

   Cynodon dactylon (L.) Pers.

If plant is > 20 cm tall and number of branches greater than 5 in one or more whorls, consider also couplet [47].
In a planted lawn situation, see Page 21.

Spikelets narrowly ovate, pediceled, pedicels unequal, spikelets falling at maturity with glumes. Leaf arrangement distinctly alternate. Some Digitaria spp. .. .

Cynodon nlemfuensis Vanderyst

Although rare, these two species may hybridize in Hawai‘i (Faccenda, et al., 2024)

Culms stiff, "woody". Inflorescence of 5-17 spikes in one to five whorls. Giant star grass [HAW - NAT]

Cynodon aethiopicus Clayton & J.R. Harlan

Spikelets under 6 mm (1/4 in) and crowded or not on the rachis of the raceme. Unequal glumes remaining on the rachis after the spikelet falls away .. .

Spikelets large (to 13 mm or 1/2 in) and so dense on a rachis at maturity that the rachis itself is obscured. Racemes may curve inward at tips. Spikelets not disarticulating at maturity. { Resembles the very common E. eleusine but much more robust; a large grass; seeds are exposed at maturity and edible; plant is grown as a crop in parts of Africa and Asia. ragi, ragimillet [GUM - NAT]

   Eleusine coracana (L.) Gaertn.

Spikelets strongly laterally compressed, linear or lanceolate in outline on short pedicels crowded in two rows on rachis. Lower lemma with a bent awn, twisted at the base. Glumes keeled. Ligule a fringed membrane .. .

Spikelets rounded or linear, not strongly compressed, on short or no pedicels. Glumes not keeled. Ligule a membrane or dense row of cilia. Chloris spp. .. .

Medium-size, grey-green grass; plant densely pubescent. Racemes 3 to 6. Leaves slender. Rachis trigonous. Spikelets 3.3-4.8 mm long, inserted into alternating notches in the rachis. Tuft of short hairs at base of each spikelet. Apex of lower lemma bifid. { Abundant perennial grass of grasslands and savanna on Guam. [GUM - END]

Dimeria chloridiformis (Gaud.) K. Schum. & Lauterbach

Dimeria ornithopoda Trinius