Flora of New Zealand | Taxon Profile

Classification

Class

Magnoliopsida Brongn.

Order

Malpighiales Martius

Family

Salicaceae

Genus

Salix L.

Subordinate Taxa

Nomenclature

Scientific Name:

Salix subgen. Vetrix (Dumort.) Dumort., Bull. Soc. Roy. Bot. Belgique 1: 141 (1862)

Synonymy:

≡ Salix sect. Vetrix Dumort., Bijdr. Natuurk. Wetensch. 1: 55 (1826)

Type Taxon:

Salix caprea L.

Vernacular Name(s):

osier; sallow; shrub willow

Description

Multi-stemmed small trees, erect shrubs, or low-growing shrubs. Terminal branchlets erect. Stipules small to large (up to 9 mm long), persistent or deciduous. Leaves alternate (varying between opposite and alternate in Salix purpurea). Glands absent from the distal end of the petiole. Mature leaves elliptical, narrowly elliptical, narrowly ovate, narrowly obovate, or linear, length to width ratio 1.2–5.5:1 in most species but 6–27:1 in a few species (S. eleagnos, S. schwerinii, S. viminalis, S. petiolaris, and S. purpurea), not falcate; margins serrulate, serrate, or entire, undulate or not, revolute or not; hairs on emerging leaves usually dense, persisting or deciduous in mature leaves, hairs on mature leaves absent to dense. Willow sawfly galls mostly absent (may be present in S. acutifolia, S. lasiolepis, S. triandra). Catkin emergence usually precocious, less commonly coetaneous or serotinous. Female flower bracts persistent or deciduous. Flower bracts either bicoloured (crimson before flower emergence, turning dark brown to black distally, hyaline or crimson proximally) or hyaline-green, concave or plane, sometimes recurved at apex. Male flowers with 1–2(4) nectaries. Male flowers with 2(–9) stamens, filaments usually free, partly fused, or fully fused, but the anthers not joined (in S. gracilistyla and S. purpurea), usually with hairs present at the base of filaments. Anthers red or yellow before opening. Female flowers with 1 nectary. Ovary glabrous to densely hairy, sessile or on a stipe, tapering to a short or long style; stigmas hyaline, pale green, yellow-green, or tinted red.

Key

1	Hairs on lower surface of mature leaves moderately dense to very dense and persistent to some degree (i.e. mature leaves never glabrous)	2
	Hairs on lower surface of mature leaves absent, sparse, not persistent	18
2	Hairs on lower leaf surface straight and appressed (short- to long-silky hairs)	3
	Hairs on lower leaf surface crinkled and partly erect (woolly)	8
3	Lower leaf surface obscured by dense hairs; hairs giving lower leaf surface a silky sheen	4
	Lower leaf surface visible between hairs (sparsely to moderately densely hairy); lower leaf surface lacking a silky sheen	6
4	Leaves 25–30 mm long, narrowly elliptical	repens
	Leaves 70–235 mm long, very narrowly ovate	5
5	Stipules persistent, 17–18 mm long, 5 mm wide, twisted; flower bracts bicoloured: brown to black and hyaline; only male plants present in New Zealand	schwerinii
	Stipules not persistent, when present 2–7 mm long, 1–3 mm wide, not twisted; flower bracts crimson turning black at the apex; style arms 0.9–1.4 mm, unlobed or lobed to their bases and appearing equally 4-lobed	viminalis
6	Leaves narrowly ovate; vigorous branchlets fused into flattened fascicles	udensis ‘Sekka’
	Leaves narrowly obovate; branchlets never fasciculate	7
7	Lower leaf surface hairs persisting only on the midvein; female plants only in New Zealand	myrsinifolia
	Lower leaf surface hairs persisting; male plants only in New Zealand	basaltica
8	Leaves 3–12(20) mm wide, length to width ratio 6–26:1; gland of leaf margin tooth displaced to upper leaf surface rather than margin; style arms 0.6–1.4 mm long	9
	Leaves 18–78 mm wide, length to width ratio 1.2–3.0:1 (S. cinerea × S. viminalis hybrids 3.6–5.8:1); gland of leaf margin tooth on the leaf margin; style arms 0.2–0.8 mm long	11
9	Leaves 3.0–4.5 mm wide; length to width ratio 6–12:1; flower bracts uniformly yellow-green, never turning black; style arms 0.6–0.8 mm long, lobed about half their length; ovary glabrous	eleagnos
	Leaves 8.5–57 mm wide; length to width ratio 3–15:1; flower bracts crimson turning black at the apex; style arms 0.7–1.4 mm long, lobed or unlobed; ovary hairy	10
10	Current year’s and year-old branchlets glabrous; mature leaves glabrous or almost glabrous; hairs on stipe and ovary apex only; wood ridges absent	myricoides
	Current year’s and year-old branchlets hairy; leaves persistently and moderately densely tomentose below; ovaries densely hairy; wood ridges often present	11
11	Leaf base cordate	12
	Leaf base cuneate to rounded	13
12	Hairs on lower leaf surface dense, silvery, unbranched	hookeriana
	Hairs on lower leaf surface sparse, some brown hairs present, some hairs branched	cardiophylla
13	Mature leaves 95–145 mm long; year-old branchlets 3.0–5.0 mm diameter*; hairs silvery, never brown, denser on veins than lamina, and on veins straight; single plants with both male and female flowers present (mixed on catkins or mixed on branches); flowering in July	aegyptiaca × caprea
	Mature leaves 32–120 mm long; year-old branchlets 2.0–3.8 mm diameter*; hairs on lower leaf surface sometimes with brown hairs present, equally dense on lamina and veins; plants either completely male or female; flowering September–November	14
14	Wood ridges on branches† either absent or sparse and 2–8 mm long	15
	Wood ridges on branches† dense and 8–60 mm long (averaging 17–25 mm long)	16
15	Leaves 22–46 mm wide; year-old stems 1.9–3.5 mm diameter*; style base 0.2–0.4 mm long and not covered by hairs of the ovary; silver hairs only present on leaves	×reichardtii
	Leaves 53–61(70) mm wide; year-old stems 3.5–5.0 mm diameter*; style base very short and covered by hairs of the ovary; brown hairs sometimes mixed with silver hairs on upper surface of leaves	caprea
16	Year-old branchlets 2.2–3.9 mm diameter (averaging 2.7 mm diameter*); brown hairs mixed with silver hairs on either surface of leaves; leaves 17–35 mm wide, on average 25 mm wide; style arms 0.6–0.7 mm long, unlobed, stipe 1.3 mm long	atrocinerea
	Year-old branchlets 2.8–4.6 mm diameter; silver hairs only present on leaves (occasionally a few brown hairs present in S. ×calodendron); leaves 27–57 mm wide; style arms unlobed or completely bilobed	17
17	Mature leaves 65–103 mm long, petiole 4–12 mm long; year-old branchlets 2.8–4.4 mm diameter (averaging 3.1 mm diameter*); hairs on underside of mature leaves moderately dense; style arms 0.7–0.8 mm long, stipe 1.4–2.2 mm long; catkins male or female	cinerea
	Mature leaves 100–173 mm long, petiole 7–23 mm long; year-old branchlets 4.1–4.6 mm diameter; hairs on underside of mature leaves rather sparse; style arms 0.7–1.4 mm long; stipe 0.7–1.6 mm long; catkins female only	×calodendron
18	Some leaves and catkins on any branch opposite; stamen filament one, ovary hairy, sessile, with style arms 0.3 mm long; petiole not enlarged, leaves entire except sometimes teeth near the leaf apex, margins plane; stipules absent	purpurea
	Leaves and catkins never opposite, stamen filaments two per flower; ovary glabrous (if present), style arms 0.4–0.6 mm long (if present), leaf margins usually serrated (entire in S. magnifica), usually recurved; stipules may be present on young leaves in summer, persisting or not	19
19	White waxy bloom present on 2–3-year-old branchlets	20
	Waxy bloom absent from 2–3-year-old branchlets	21
20	Leaves 16–30 mm wide; young green branchlets and emerging leaves glabrous; petiole not enlarged at base; branchlets 2.6–3.5 mm in diameter*; flower bud scales 14–16 mm long; male plants only in New Zealand	acutifolia
	Leaves 23–39 mm wide; young branchlets and emerging leaves hairy; petiole enlarged at base; branchlets 3.0–4.5 mm in diameter*; flower bud scales 7–12 mm long; both sexes in New Zealand; ovaries glabrous	daphnoides
21	Leaves 45–85 mm wide	22
	Leaves 8–39 mm wide	24
22	Leaf margins entire	magnifica
	Leaf margins serrate	23
23	Upper leaf surface finely bullate; leaf base without marginal glands; male catkins 29–31 mm long; most flower bracts staying green but some turning black	reinii
	Upper leaf surface smooth; leaf base with obvious marginal glands; male catkins 13–17 mm long; flower bracts all turning black in the distal half	apennina
24	Stamens with 1 filament below a pair of anthers; flower bracts completely black, glabrous; petiole enlarged at the base, red	gracilistyla ‘Melanostachys’
	Stamens with 2 filaments, each with a single anther; flower bracts either uniformly green or bicoloured black and hyaline, hairs sparse to dense; petiole base not enlarged	25
25	Leaves glaucous below, margins entire, recurved, leaf galls sometimes present	lasiolepis
	Leaves not glaucous below, margins serrate, plane, leaf galls never present	26
26	Leaves 8 mm wide and linear; stipules tiny and not persistent; male plants only in New Zealand	exigua
	Leaves 10–39 mm wide, elliptical to ovate; stipules large and persistent; both sexes or male plants only in New Zealand	27
27	Stamens 3, male and female plants in New Zealand	triandra
	Stamens 2 or female plants only in New Zealand	28
28	Mature leaf lamina 87–122 mm long, 10–24 mm wide, length to width ratio 5.5–9.7:1	eriocephala × petiolaris
	Mature leaf lamina 112–128 mm long, 31–43 mm wide, length to width ratio 2.9–4.1:1	eriocephala

* = diameter of year-old branchlet measured 150 mm below branchlet apex.

† = wood ridges on 1–3 year-old branchlets of 10–30 mm diameter stripped of the bark.

Biostatus

Exotic

Number of species and named hybrids in New Zealand within *Salix* subgen. *Vetrix* (Dumort.) Dumort.
Category	Number
Exotic: Fully Naturalised	8
Exotic: Casual	5
Exotic: Cultivated	16
Total	29

Notes

Old World (Eurasian) shrub willows present in New Zealand: Salix acutifolia, S. aegyptiaca × S. caprea, S. apennina, S. atrocinerea, S. basaltica, S. ×calodendron, S. caprea, S. cardiophylla, S. cinerea, S. daphnoides, S. ×dichroa, S. eleagnos, S. gracilistyla, S. magnifica, S. myricoides, S. myrsinifolia, S. purpurea, S. ×reichardtii, S. reinii, S. repens, S. ×rubra, S. schwerinii, S. triandra, S. udensis, and S. viminalis. As well there are a number of hybrids where either S. purpurea or S. viminalis is the recognisable parent but the other parent is not obvious.

New World (North American) shrub willows present in New Zealand: Salix eriocephala, S. exigua, S. hookeriana, S. lasiolepis, and S. myricoides.

Bibliography

Dumortier, B.C.J. 1825: Verhandeling over het geslacht der wilgen (Salix) en de natuurlijke familie der Amentaceae. Bijdragen tot de Natuurkundige Wetenschappen 1(1): 44–61.

Dumortier, B.C.J. 1862: Monographie des saules de la flore Belge. Bulletin de la Société Royale de Botanique de Belgique 1: 130–147.

Salix subgen. Vetrix (Dumort.) Dumort.