Agrostis castellana Boiss. & Reut.
dryland browntop
Grey-green, rather fine-leaved perennials, forming tufts 30-90 cm, with long slender rhizomes; branching intravaginal. Leaf-sheath glabrous, brownish green or purplish. Ligule 0.7-2 mm, or up to 3 mm in culm leaves, taller than wide, somewhat tapered or rounded, minutely ciliate. Leaf-blade 4-16 cm × 1.5-4 mm, flat, finely scabrid, adaxially finely ribbed; margins scabrid, tip acute. Culm erect, internodes glabrous. Panicle 10-24 cm, linear-lanceolate to spreading, later more contracted; rachis, branches and pedicels sparsely scabrid to almost smooth. Spikelets 2-3 mm, grey-green to purplish; terminal spikelets usually with awned, 5-nerved lemmas, and lateral spikelets with awnless, 3-5-nerved lemmas. Glumes subequal, elliptic-lanceolate, acute or acuminate; lower with keel scabrid in upper ½, upper slightly shorter, smooth to scabrid on keel near tip. Lemma 1.6-2.2 mm, (3)-5-nerved, ovate-oblong, truncate-lobulate, the outer lateral nerves usually minutely excurrent, awned lemmas often with a few hairs in lower ½ near margin, awnless lemmas glabrous; awn, when present, from near base of lemma and ˜ lemma or up to twice length of lemma, occasionally awn very minute, middorsal or subapical and not projecting beyond lemma. Palea ½-⅔ length of lemma, apex shallowly bifid. Callus with minute tufts of hairs on either side, or sometimes glabrous in spikelets with awnless, 3-nerved, glabrous lemmas. Rachilla sometimes prolonged and tipped with a small tuft of hairs in awned spikelets. Anthers 1-1.5 mm. Caryopsis c. 1 × 0.4 mm.
N.: throughout; S.: throughout, but most common in Canterbury and Otago; C. Lowland to montane on light soils and dry, often stony waste ground, roadsides, track margins, and river terraces; sometimes found in dry hill-country grassland with A. capillaris.
Naturalised from Mediterranean.
In typical A. castellana, all spikelets are awned from near the base of the lemma and the lemma is pubescent on the margins of the lower half, and 5-nerved, the outer lateral nerves being conspicuously excurrent (to 0.5 mm), with the rachilla shortly prolonged and bearded, and the callus laterally bearded with hairs to 0.6 mm. However, variants of A. castellana occur lacking pubescence on the back of the lemma, or the awn, or prolonged rachilla, but still recognised by the bearded callus. Some of the awnless variants have 3-nerved lemmas. From these variants of A. castellana there is a series of intermediates to florets which would be recognised as A. capillaris. Plants of N.Z. dryland browntop are often found with spikelets of two kinds in the same panicle. The terminal spikelets of the branches and branchlets have basally awned lemmas, excurrent lateral nerves, and a hairy callus, whereas the lateral spikelets are awnless with a glabrous callus and have 3-4-nerved glabrous lemmas with only minutely excurrent lateral nerves. The description of A. castellana encompasses all these variants, which probably result from hybridism with A. capillaris, and the two spp. cannot be clearly separated by spikelet characters.
Dryland browntop is now used as a specialist lawn grass; because it is a frequent contaminant of browntop lawn seed it has become a common garden weed.
Dryland browntop was first recorded for N.Z. as a native ecotype of A. capillaris originating in Canterbury and differing from normal browntop in having finer, grey-green leaves, a stronger rhizome, longer ligule, and more compact, coarser panicles.
