Arum italicum Mill.
Italian Arum
Erect tuberous perennials, 25-60 cm high, leaves appearing in late autumn and through winter; flowering in spring, the leafless scape with scarlet berries conspicuous in late summer. Tuber c. 4 cm diam., producing small tubers. Leaves large; laminae hastate, to 30 cm long, dark green with lighter yellow-green midrib and main veins; petioles 20-40 cm long, lower half membranous, sheathing, purple-tinged. Spathe ± translucent, pale whitish-green, purple-tinged near base especially on inside, c. 30 × 15 cm; scape < petiole, greenish to reddish. Spadix ± ⅓ of spathe; basal female zone ± 2 cm long, a few sterile flowers above them; upper male zone c. 0.8 cm long, with narrow band of sterile flowers below terminal, stipitate, yellow sterile appendage. Berries 1 cm diam., bright red.
N. Scattered, S. Nelson - Little Wanganui, Nelson City; Marlborough - Okaramio; Canterbury - Christchurch, Garden escape, well-established in N. Id especially in damp places; in S. Id, rare to occasional in waste places and untended land.
First record: Mason, Moar and Cooper 1950: 86, as "Arum sp., either Arum maculatum L., or a closely allied species."
First collection: Kopu, Thames, well-established in low-lying paddock, N.M. Adams, 31.3.1945 (CHR 49515).
The dark green leaves of A. italicum with silvery or light green midrib and main veins are distinct as also are the greenish-white spathes. Juvenile leaves are lanceolate, adult leaves large and hastate, shading and smothering plants below.
A persistent colony- or clump-forming garden escape, A. italicum is established in older gardens, about hedgerows and farm shelter trees, in old farm orchards, and in grassland near homesteads and on sites of former domestic gardens. It is most aggressive in gardens and cultivated sites, new plants developing from small tubers, of which up to 30 arise from each main tuber; by contrast, increase of clumps in undisturbed grassland is slow by vegetative means. Spread is by seed too, and observations in N.Z. suggest that domestic poultry and wild birds may be agents of dispersal: seed viability is high, but seedlings tolerate little competition, see Thompson (N.Z. Weed & Pest Control Conf. Proc. 29, 1976, 110-113).
The sap is irritant and has a burning effect on animal tissue, but fortunately the plant is rarely grazed by livestock.
