Flora of New Zealand Series

Plagianthus lyallii Gray ex Hook. f. Fl. N.Z. 2, 1855, 326.

Gaya lyallii Baker in J. Bot., Lond. 1892, 137.

G. lyallii var. ribifolia Kirk Stud. Fl. 1899, 72.

G. ribifolia Ckn. in T.N.Z.I. 33, 1901, 272.

Type locality: Canterbury. Type: K, Lyall.

Slender deciduous tree up to 6 m. or more tall, with branchlets, lvs and infl. ± densely clad in stellate hairs. Juvenile plants with lvs on slender petioles up to ± 5 cm. long; lamina 2-7 × 2-6 cm., thin, ovate to suborbicular, truncate to cordate, us. deeply 2-5-lobed; teeth doubly, deeply crenate. Adults with lvs on stouter petioles (1)-2-4 cm. long; lamina submembr., (3)-5-10 × 2-5 cm., broad-ovate, truncate to cordate at base or sts rounded both at base and apex; us. deeply doubly or trebly crenate, sts incised-crenate or lobed as in juveniles. Fls 2-3-(4) cm. diam., in cymose, ebracteate, 2-5-fld fascicles to solitary, on slender pedicels (1)-2-3-(5) cm. long. Calyx cupuliform c. 7-10 mm. long, densely pubescent without; teeth 5 (occ. small accessory teeth are present). Petals us. 5, obliquely obovate, us. notched, shortly clawed, up to 2 × 1 cm. Staminal column ± 7 mm. long; filaments 3-5 mm. long, anthers purple. Styles filiform, stellately pilose; stigma obliquely capitate to decurrent. Carpels 10-15, pubescent, compressed, obscurely winged; seeds much compressed.

DIST.: S. Montane to subalpine upper forest margins, sts on stream terraces, sts forming groves, east of divide, from lat. 41° 30' to lat. 45°.

FL. 11-2. FT. 1-3.

Cockayne (T.N.Z.I. 33, 1900, 272) points out that this sp. and H. glabrata do not meet, although in places they occur not more than c. 7 Km. apart. Allan (J. Ecol. 14, 1926, 79) noted that H. lyallii occurred on Mount Peel, Canterbury, and not H. glabrata, though the climate well suited the latter. He added: "In dense shade by the sides of streams the Mt. Peel plant, elsewhere typical ribifolia [H. lyallii] becomes a shrub the leaves of which are almost identical with those of P. lyallii [H. glabrata] being much more acuminate, and having the pubescence practically confined to the veins. Rarely one finds specimens showing both forms of foliage. It would seem that research is required to determine whether we are not, after all, dealing with a species sufficiently plastic to adapt itself to the very different conditions of habitat in which the two forms grow." Sprague and Summerhayes (loc. cit. 220) comment: "the differences between the two species are not confined to the leaves, additional diagnostic characters being afforded by the stigmas and fruits. These latter differences do not seem to afford any support to Dr. Allan's suggestion." With this I agree, though the differences are not quite so clear-cut as concluded from the material available to Sprague and Summerhayes.