Deciduous tree up to c. 10 m. tall, with branchlets terete, at first sparsely stellate-pubescent; bark pale to brownish. Juvenile plant with lvs on very slender petioles up to c. 2 cm. long; lamina thin, 1-3 × 1-3 cm., of ovate to suborbicular order, cordate, irregularly deeply lobed, teeth crenate-dentate, sts apiculate; passing gradually to mature form and occ. appearing on fully adult plants. Adults with lvs glab. or nearly so when mature on slender petioles (2)-5-7 cm. long; lamina subcoriac., 5-14 × (2)-10 cm., very broad-ovate to ovate-lanceolate, acuminate (sts prolonged into "drip tips", sts broadly rounded at apex), deeply cordate to truncate at base, crenate-dentate; teeth obtuse to acute, sts apiculate. All forms may occur on the same plant. Fls up to ± 4 cm. diam., in cymose fascicles of 2-5 or solitary; pedicels 2-3 cm. long. Calyx cupular, 5-7 mm. long, densely stellate-pubescent without; lobes 5, triangular, acute, ± 3-4 mm. long. Petals white, us. 5, shortly clawed, obovate, notched or entire. Staminal column 5-7 mm. long; filaments ± 5 mm. long, anthers purple. Carpels 10-15, pubescent, ± 3 mm. long; style branches ± 6 mm. long, stellately pilose. Stigmas ± obliquely capitate to slightly decurrent. Fruiting carpels not winged, or with vestigial wing only.

DIST.: S. Lowland to subalpine forest and shrubland throughout, mainly west of divide, often forming groves in avalanche paths and on slips.

Type locality: Milford Sound. Type: K, Lyall.

HYBRIDISM

There is some field evidence that H. populnea may cross with H. sexstylosa, but both suggested parents are very complex, and only controlled breeding tests could decide the matter.

Cockayne (T.N.Z.I. 56, 1926, 23) described his Gaya allanii from specimens collected at Peel Forest, Canterbury. His description includes: "Folia juvenilia ± 1·5 cm. longa, ± 8 mm. lata, petiolis ± 5 mm. longis, ovata, crenato-serrata, acuta, sparsis stellatis pilis induta. Folia matura ± 5 cm. longa, ± 2 cm. lata, ovato-lanceolata . . . grosse et incise bi-serrata vel crenato-serrata . . . Flores 3-5 fasciculati . . . pedunculi graciles, ± 1·5 cm. longi, stellato-pubescentes . . . Ovarium ovoideum, ± 4 mm. longum, ± 2 mm. diam., plerumque 7-, interdum 6- vel 8- loculatum." Study of other populations in Canterbury showed that G. allanii was only one of the forms resulting from H. angustifolia × lyallii. The matter was discussed by Allan (Genetica 8, 1926, 371).

In K are specimens, garden grown, said to be of origin (a) glabrata × sexstylosa and (b) lyallii × populnea.