Senecio wairauensis Belcher
fireweed
Erect annual to short-lived perennial herb. Mid cauline lvs almost glabrous or with few scattered hairs on both surfaces, apetiolate or cuneately narrowed to appear petiolate, narrow-oblong, elliptic, or narrow-obovate, shallowly pinnately lobed and denticulate to lyrate-pinnatifid or 1-pinnatifid with ± oblong, few-toothed (rarely many-toothed) segments, amplexicaul and dentate at base or rarely not amplexicaul, (4)-6-13 × (1)-2-5 cm. Uppermost lvs smaller, often lanceolate, usually 1-pinnatifid, sometimes only dentate or entire. Supplementary bracts 3-6, 1-2 mm long. Involucral bracts (8)-12-13-(14), glabrous, 6-7-(8) mm long. Ray florets 0. Disc yellow, 2-3 mm diam. Achenes subcylindric, narrowed to and constricted below apex, glabrous or with scattered hairs in 1-3 rows in narrow grooves between broad ribs, (2.2)-3-4-(5) mm long.
N.; S.: throughout; St.
Endemic.
Stony or wet sites in open forest, forest margins and clearings, shrubland, grassland, or disturbed areas, mostly from 600-1500 m but reaching sea level in some areas.
FL Dec-May.
S. wairauensis is very variable in lf shape, with entire forms approaching S. dunedinensis and more dissected forms approaching S. biserratus (Fig. 30). S. wairauensis differs from S. dunedinensis in the longer bracts and achenes and from S. biserratus in the more numerous bracts and usually in the apparently petiolate lf bases. Material from St. and parts of Fiordland is quite distinctive in having very dissected lvs [Fig. 30, and see Wilson, H. D., Stewart Island Plants (1982)], short achenes (2.2-3 mm) and long bracts (7-8 mm), and should perhaps be accorded taxonomic recognition. Montane and alpine plants from N. South Id have less divided lvs than typical S. wairauensis (Fig. 30), but do not differ in other characters; they probably do not merit taxonomic recognition. S. wairauensis was treated by Allan (1961) within Erechtites as E. wairauensis. Drury (op. cit.) concluded that Allan's var. robusta does not warrant recognition.
