Reeder, J. R. in Jour. Arnold Arb. 29: 313. 1948

JOUR. ARNOLD ARB. VOL. XXIX

PLATE IV

HERBARIUM
OF
YALE UNIVERSITY

GRAMINEAE-PANICOIDEAE OF NEW GUINEA

(Drawn from type specimen)

PLATE IV

Isachne obecta Reeder (Brass 7242): a. habit, × ½; b. complete spikelet; c & d. two views of spikelet with glumes removed (b-d, × 10).

7. Isachne obecta sp. nov. PLATE IV.

Perennis 30-45 cm. alta; culmis caespitosis, glabris, suberectis vel ad-
scendentibus, circiter 1 mm. diametro; nodis glabris, eis infra medium
culmi saepe ramiferis; vaginis glabris quam internodiis brevioribus, mar-
ginibus ciliatis; ligula ad lineam ciliatam 2-3 mm. longa reducta; laminis
lanceolato-linearibus, 2-6 cm. longis, 3-6 mm. latis, acutis, subcordatis,
praecipue subtus plus minusve villosis, supra saepe pilis paucis adspersis,
marginibus scabris; panicula longe exserta, 5-8 cm. longa, contracta,
ramis rigidis, erectis, floribus confertis; rhachi ramisque teretibus, glabris
vel sub lente minute scaberulis; pedicellis clavatis; spiculis glabris, 1,5
mm. longis; glumis aequalibus, ellipticis vel plus minusve obovatis, nervis
obscuris, circiter 7, marginibus scariosis, paene flosculas obtegentibus;
flosculis aequalibus et fructiferis, ellipticis, nitidis, rhachilla complanata
junctis, floscula infima interdum paulum dorso-complanata.

BRITISH NEW GUINEA: Western Division: Palmer River, 2 miles below junction with Black River, alt. 100 m., Brass 7242 (A, TYPE, US) July, 1936 (common in native gardens).

In some respects this species suggests *Isachne Brassii*, but it is readily
distinguished by the more upright firmer culms, somewhat villous blades,
the much contracted panicle, and the slightly smaller spikelets with glumes
almost completely covering the florets. The florets, moreover, are of
almost exactly the same size and the tip of the upper is borne slightly above
the lower. In *I. Brassii* the tips of the florets are borne at the same height
and the upper floret is smaller and more convex on the back. The new
species may also be compared with *I. villosa*, but that species has papillose-
roughened or pubescent florets which are joined by a terete rachilla.

The specific epithet refers to the fact that the florets are almost com-
pletely covered by the glumes.

Yale University Herbarium

YU.000882