Dactyloctenium

Dactyloctenium is a genus of herbaceous plants belonging to the Poaceae family. It is native to Africa and Australia.

Description

They are annual plants, spreading by short runners and forming radial mats, the erect portions of the stems 2–50 cm long, glabrous, solid; conspicuous knots; hermaphrodite plants. Pods carinate, glabrous to pustular-hairy; ligule a membrane, ca 0.5 mm long; blades linear, 1–7 cm long and 1–7 mm wide, papillose-villous, occasionally glaucous. Inflorescence a whorl of 2–4 subsessile spikes, unilateral, the axis extended like a bare point beyond the spikelets; spikelets ca 4 mm long, gray to purplish, sessile, densely imbricated in 2 rows along the underside of the rachis, laterally compressed, carinate, with several bisexual florets, the uppermost sterile; disarticulation generally above lower glume, remainder of spikelet deciduous as a unit and upper glume and rachilla lemmas deciduous, paleas remaining; glumes 2, 1-veined, broad, the lower one ovate, 2 mm long, apiculate, the upper one broadly ovate, ca 3 mm long, truncate, with a short, thick, divergent awn; florets 3; lemmas strongly compressed, ovate, 2–3 mm long, acuminate, keel strongly arched, scabrid, midvein conspicuous, green, lateral veins inconspicuous; paleas 2-carnate, 3-veined; lodicules 2, truncated; stamens 3, the anthers ca 0.4 mm long, yellow; styles 2. Fruit a utricle; seed broadly ovate, truncate, strongly ridged; pericarp thin and delicate, evanescent.

Taxonomy

The genus was described by Carl Ludwig Willdenow and published in Enumeratio Plantarum Horti Botanici Berolinensis,... 2: 1029–1030. 1809. The type species is: Dactyloctenium aegyptium (L.) Willd.

Etymology

The name of the genus derives from the Greek daktylos (finger) and ktenion (small comb), alluding to the fingered inflorescences.

Cytology

The basic chromosome number of the genus is x = 10 and 12 with somatic chromosome numbers of 2n = 20, 36 and 48, since there are diploid species and a polyploid series.

Species

Accepted

1. Dactyloctenium aristatum
2. Dactyloctenium aegyptium
3. Dactyloctenium australe
4. Dactyloctenium buchananensis - Queensland
5. Dactyloctenium capitatum Madagascar
6. Dactyloctenium ctenoids
7. Dactyloctenium germinatum
8. Dactyloctenium giantum
9. Dactyloctenium hackelii - Socotra
10. Dactyloctenium pilosum
11. Dactyloctenium radulans
12. Dactyloctenium robecchii
13. Dactyloctenium scindicum

previously included

see Acrachne Eragrostis Harpochloa

• Dactyloctenium falcatum - Harpochloa falx
• Dactyloctenium henrardianum - Acrachne henrardiana
• Dactyloctenium nitidum - Eragrostis nitida
• Dactyloctenium perrieri - Acrachne perrieri
• Dactyloctenium verticillatum - Acrachne racemosa