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CPIE Notebook Project - Common Hawaiian Grasses Page 13


Key to Genus Chloris Sw.

Chloris barbata hanit

Grasses of the genus Chloris are sometimes called "fingergrasses" because the spikes are arranged like fingers (digits) at the top of the culm. The spikelets have several common characteristics that usually can be observed without magnification, though magnification helps: the spikelets have awns, typically 1 to 3 per spikelet, and these are usually very conspicuous, but may require magnification in some species; the spikelets are secund or unilaterial (arranged in pairs on one side of the rachis); the spikelets are attached directly to the rachis or by very short pedicels and fall from the rachis above two glumes of slightly unequal size, so these small, paired bracts are left behind as the infloresence drops the seeds, providing one with an easy glimpse of the glumes. The ligule is a dense row of short hairs.

Six species of Chloris are known to be present in Hawai‘i (Clayton & Snow, 2010) and many are commonly encountered as weeds in lawns and especially at disturbed sites. All Chloris species in Hawai‘i are naturalized species (that is, none is native) and several are very common in lowland dry locations (Chloris barbata especially).

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45a (41) Spikes clustered, held upright, typically 2.5 inches (6 cm) or less long, sometimes longer. Floret (first lemma actually) crowned with long hairs (ciliate) and long awns [46]
45b

Spikes spreading or ascending, typically 3 inches (6 cm) or more long, sometimes shorter. Floret with no or only short hairs on lemmas and with or without awns.

[47]
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46a (45) closeup of spikes

Magnifying Lens Inflorescence of 5-15(-22) spikes. Each spikelet with three long awns. Two sterile florets orbicular, giving the spikelets a beaded appearance on close inspection; each sterile floret awned. Stems and leaves thin, stems with swollen nodes and often a red ring at each node. { Annual, medium size grass forming clumps in dry, disturbed areas, although very widespread in open areas. Swollen fingergrass. [NAT]

Chloris barbata (L.) Sw.

Figure 13B. Close-up of spikes of Chloris barbata
showing beaded appearance of spikelets and
multiple awns.

46b

Inflorescence of 4-12 feathery spikes. Each spikelet with two long awns (see Fig. 7D below). Two sterile florets not orbicular and only one awned. { Annual, medium size grass forming clumps in dry, disturbed areas. Feather fingergrass. [NAT]

Chloris virgata Sw.
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47a (45) Spikelets with all awns short, the longest about or only a little longer than the length of a spikelet. [48]
47b

Spikelet with at least one long awn greater than twice the length of spikelet (0.5 to 1.6 cm long). Inforescence of 5 to 15 ascending or lax racemes.

[49]
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48a (47) Inflorescence of (5-)7-20 ascending or lax spikes. Spikelet with 3 or 4 florets (2-3 sterile) and several short awns, one a very short extension of the strong mid-vein of the 2nd glume. First lemma with a tuft of short hairs. Ligule a short (0.5 mm) membrane and long hairs (ciliate). { Medium usualy erect, perennial grass of open, disturbed areas, verges, and pastures. Rhodes grass. [NAT]

Chloris gayana Kunth
48b

Inflorescence of 4-13 widely spreading spikes. Spikelets with but one sterile floret.

[50]
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49a (47)

Racemes between 5 and 8 cm long, somewhat lax. Spikelet narrow, acute, light green or yellow, with two obvious awns, at least one awn approaching 3/8 in (1 cm) in length. Glumes similar, but one clearly shorter than florets. { Medium-size, loosly-tufted annual in mostly mesic, disturbed sites, verges, and fields. Radiate fingergrass. [NAT]

Chloris radiata (L.) Sw.
49b

Racemes between 5 and 23 cm long, spreading (outward to downward radiating). Spikelet wedge-shaped, dark brown or black. Sterile floret truncate. Glumes about equal in length to florets. Tip of leaves blunt. Windmill grass. { perennial, with stolons. [NAT]

Chloris truncata R. Br.
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50a (48) & (45)

Spikelet narrowing towards tip (accuminate), light green to tan in color.

[51]
50b

Spikelet blunted at tip (wedge-shaped or cuneate), dark brown or black in color. Inflorescence of 5 to 15 spikes (or racemes with short pedicels) radiating from a common point on the culm and radiating outward, each spike between 5 and 23 cm long. Tip of leaves blunt. Windmill grass. [NAT]

Chloris truncata R. Br.
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51a (50) Spikes 1.5 to 3.5 in (4 to 9 cm) long. {small, perennial speading grass with widely spreading racemes, resembling Bermuda grass. Stargrass. [NAT]

Chloris divaricata var. cynodontoides (Balansa) Lazarides
51b

Spikes 6 to 8 in (15 to 20 cm) long.{small, perennial speading grass with widely spreading racemes. Stargrass. [NAT]

Chloris divaricata var. divaricata R. Br.


GRASS PHOTOS
[CLICK ON THUMBNAIL TO OPEN AN ENLARGED IMAGE]
thumb for feather fingergrass image

Fig. 13C. Dried flower head of Chloris virgata illustrating several diagnostic characteristics: spikelets with two awns and a crown of stiff hairs; spikelets falling from rachis leaving glumes (one short and one long) still attached to rachis.

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