Nomenclature
Scientific Name:
Salix hookeriana Barratt ex Hook., Fl. Bor.-Amer. [Hooker] 2, 145, Pl. 180 (1838) – as Hookeriana
Synonymy:
Type: "AE Douglas, Saskatchewan, near the grand rapids", most likely a labelling error, the correct details being: "N.W. Coast of America, Scouler" fid. Dorn (1994, p. 92). Lectotype (chosen by Dorn, 1994, p. 92): K 1079501, image seen.
Vernacular Name(s):
coastal willow; dune willow; Hooker's willowArgus 2010
 Description

Wood ridges absent. Current year's branchlets green, densely velvety. Year-old branchlets greyish red to red-brown (UCL19–43), very sparsely tomentose, 3.4–3.5 mm diameter. Bud scales 8.8–11.7 mm long, 3.5–5.5 mm wide, 3.0–3.5 mm deep, ovoid, with slight angles, dark red to red-brown (UCL16–43), glabrous to very sparse long-silky hairy. Stipule absent from spring leaves, up to 18 mm long in summer leaves, not persisting. Petiole 12–17 mm long, pale yellow, densely tomentose, glands absent, base of petiole not enlarged. Emerging leaves green, with dense tomentum. Proximal leaves entire. Leaf lamina 95–104 mm long, 48–60 mm wide, length to width ratio 1.7–2.1:1, ovate; base cordate to truncate; apex acute or acuminate; leaf galls absent; margins crenate, finely revolute; upper lamina surface slightly bullate due to impressed veins, dull to medium glossy, sparsely tomentose, tomentum dense on midvein, stomata absent; lower lamina surface midvein and side-veins raised, distinctly glaucous, densely tomentose. Catkins emerging before leaves. Flowering branch 49–53 mm long, 3–4 reduced leaves + 1–2 cataphylls. Male catkin 34–42 mm long, 19–23 mm diameter; catkin rachis not visible between flowers. Flower bract 2.4–2.8 mm long, 1.0–1.3 mm wide, red on emergence; apex turning black, hyaline below, flat; apex acute to obtuse, moderately dense long-silky hairs on surfaces and margins. Male nectary 1, 0.8 mm long, 0.4–0.6 mm wide, green. Stamens 2, filaments free, hairs absent; anthers 1.4–1.6 mm long, yellow, red at apex only.

 Recognition

The leaf lamina is large (95–104 × 48–60 mm) and ovate, on a petiole 12–17 mm long, the lamina base is cordate, the margins finely revolute and crenate but untoothed. The lower leaf surface is densely and persistently tomentose. Stipules do not persist and appear to be absent from spring leaf growth. Current year's branchlets are densely velvety, the hairs not persisting. Salix hookeriana in its native range appears to be variable in shape at the leaf base, but both clones in New Zealand have a distinctly cordate leaf base. The type does not have this feature, but it can be seen in some herbarium specimens of S. hookeriana from North America.

Most similar to Salix caprea in leaf size and shape and indumentum. The leaf base of S. hookeriana is cordate or at least truncate, while in S. caprea it is obtuse but never truncate or cordate. Salix hookeriana lacks persistent stipules, while in S. caprea they are obvious and persistent.

 Distribution

In cultivation in Southern North Island (Aokautere and Massey University) as PN685 and PN385.

 Biostatus
Exotic
 First Record

First collection: CHR 649553, T. Jones, 9 October 2017, Aokautere.

First publication: This publication.

 Phenology

Flowering: Late September–mid-October.

 Cytology

Hexaploid, 2n = 114 (CCDB based on a single count). Flow cytometry provisionally indicates that PN385 and PN685 are tetraploid.

 Bibliography
Argus, G.W. 2010: Salix. In: Flora of North America Editorial Committee (ed.) Flora of North America: Magnoliophyta: Salicaceae to Brassicaceae. Vol. 7. Oxford University Press, New York. 4–157.
Dorn, R.D. 1994: North American Salix (Salicaceae) typifications and notes. Phytologia 77(2): 89–95.
Hooker, W.J. 1834–1840: Flora Boreali-Americana; or the botany of the northern parts of British America: compiled from the plants collected by Dr. Richardson & Mr. Drummond on the late northern expeditions. Vol. 2. Treuttel & Würtz, London.