Cortaderia selloana (Schult. & Schult.f.) Asch. & Graebn.
Very tall, stout, erect tussock with sharp leaves of different colours on the two surfaces, and large plumose inflorescences. Leaf-sheath to 50 cm, thin, cross-veins evident, rolling up and eventually fracturing into short segments, abaxially with long internerve hairs denser below collar and abundant short interrib hairs, adaxially clothed above in minute hairs becoming fewer below; apical tufts 3 mm. Ligule to 3 mm. Collar white, adaxially with minute hairs as on sheath. Leaf-blade to 2 m × 2 cm, erect, arching when older, surfaces heterochromous, abaxially with caducous long (2 mm) hairs especially below and near midrib and abundant small interrib hairs, keel smooth below soon becoming very scabrid, adaxially with small weft of short hairs at base and abundant small internerve hairs; margins with some long hairs below becoming very scabrid from close-set rows of prickles. Culm to 6 m, internodes clothed in short, soft, silky hairs. Inflorescence to 1 m, plumose, variously coloured, branches erect in ⚥, rachis densely clothed in minute, soft, silky hairs longer and denser at nodes, branches and pedicels short finely stiff hairy, long hairs at axils. Spikelets of up to 6 florets. Glumes ± equal, to 12 mm, < florets, 1-nerved, violet suffused, acute or sometimes bifid, scabrid or toothed. Lemma to 15 mm, 3-nerved, produced and awn-like above but awn and mucro to 0.3 mm from between 2 small teeth, hairs to 10 mm, abundant and radiating from whole lemma in ♀ flowers but fewer, 7 mm long and radiating from base of lemma in ⚥ flowers. Palea to 4 mm, produced, keels and apex ciliate, interkeel and flanks sparsely scabrid. Callus to 1 mm, hairs to 2 mm. Rachilla to 0.25 mm. Lodicules to 0.7 mm. Anthers of ⚥ flowers to 4.5 mm, of ♀ flowers staminodes to 0.1 mm. Gynoecium: of ⚥ flowers ovary to 0.6 mm and stigma-styles to 1 mm; of ♀ flowers ovary to 1 mm, stigma-styles to 2 mm. Caryopsis to 2.5 mm; embryo 0.6 mm; hilum 1 mm. 2 n = 72.
N.; S.: widespread on roadsides, waste places, scrubland, and of more recent times in plantation pine forests; sea level to 800 m. FL mid Mar-late Apr.
Naturalised from central South America.
Natural populations comprise 51% ⚥ and 49% ♀ plants.
Although seeds are formed on ⚥ plants they are never abundant and are unlikely to give rise to many new plants; the reproductive system, thus, is chiefly dioecious.
As a weedy species in plantation forests see Gadgil, R. L., Knowles, R. L. and Zabkiewicz, J. A. Proc. 37th N.Z. Weed and Pest Control Conf.: 187-190 (1984); Gadgil, R. L. et al. N.Z. J. Forest. Sci. 20: 176-183 (1990).
Once widely planted as shelter and to a lesser extent as animal fodder.
