Flora of New Zealand Series

Australian fireweed

Erect, annual or short-lived perennial herb, up to c. 2 m tall. Stems usually glabrous or with a few fine scattered hairs, sometimes sparsely to densely setose (especially above), branched or not from base. Lower and mid cauline lvs usually sparsely hairy, especially below, sometimes glabrous or moderately hairy, apetiolate, 1-pinnatifid with the linear to lanceolate or sometimes broader segments entire or irregularly toothed to again pinnatifid, ovate to elliptic, acute to acuminate at apex, amplexicaul and usually deeply and evenly 3-fid at base, 5-13-(20) × 2-8 cm; venation pinnate. Uppermost cauline lvs smaller, often 1-pinnatisect with entire segments. Capitula in loose panicles. Supplementary bracts 3-4-(7), lanceolate, 1-3 mm long. Involucral bracts 8-13, linear, glabrous, 5-7 mm long. Ray florets 0. Disc greenish yellow, c. 2 mm diam. Achenes subcylindric, only slightly narrowed to and slightly constricted below apex, with 1 row of hairs on or beside ribs or 2-3 rows between, 1.8-2.3 mm long; pappus 5-7 mm long.

N.: common throughout; S.: known from 2 collections only, Marlborough Sounds and Lincoln (Canterbury).

Queensland, N.S.W. 1916

Waste places, coastal sites, pasture, forest margins and clearings.

FL Dec-Jun-(Aug).

Possibly poisonous (Connor 1977).

Australian fireweed is easily distinguished by the distinctive mid and upper cauline lvs which are deeply 1-pinnatifid and again pinnatifid in at least the lower segments (Fig. 30). It has previously been known in N.Z. as Erechtites atkinsoniae.

Two distinct entities can be distinguished among plants referred to S. bipinnatisectus in N.Z. S. bipinnatisectus sens. strict. has the distribution indicated above. The second entity, which comes true from seed and may occur along with S. bipinnatisectus and remain distinct, has been collected from Whangaruru North Head and Lake Ototoa (Northland) and the vicinity of Auckland City. It is distinguished by the ovate-oblong rather than linear to lanceolate segments of the less divided lower most cauline lvs (Fig. 30), the long setose hairs of the upper stem, generally by the more numerous involucral bracts, (11)-12-13 rather than 8-11, and the hairier achenes.