Willows

Salix species

Salix alba var. vitellina (White Willow or Golden Willow)
Salix alba var. alba (White Willow)
Salix babylonica L. (Weeping Willow) is the main species in WA.
Salix cinerea L. (Common Sallow)
Salix cinerea ssp. cinerea (Grey Sallow)
Salix cinerea ssp. oleifolia (Rusty Sallow)
Salix fragilis var. fragilis (Crack Willow)
Salix matsudana hybrids (New Zealand Willow or Tortured Willow)
Salix nigra Marshall (Black Willow)
Salix x calodendron (Hybrid Pussy Willow)
Salix x reichardtii Hybrid (Pussy Willow)
Salix x rubens (Basket Willow)
Salix viminalis (Basket Willow)
Synonyms - Salix caprea L. = Salix cinerea L.
Salix matsudana Koidzumi = Salix babylonica L.

Family: - Salicaceae

Names:

Salix is Latin for Willow.
Cinerea is Latin for ash coloured referring to the soft grey hairs on the underside of the leaves and greyish bark.
Fragilis is Latin for fragile and refers to the easily broken shoots.
Willow, Sallow
There are 32 different groups of Willows in Australia.
Salix fragilis var. fragilis is called Crack Willow because the brittle wood makes an cracking sound when it breaks.

Other Names:

Osier
Sallow

Summary:

Description:

Willows are trees or shrubs with single or multiple trunks, from 5 to 30 m tall, mostly deciduous with narrow leaves which are often minutely toothed. The male and female flowers are on separate plants, arranged in catkins and lack petals. The male flowers have 1-15 free stamens. The female flowers have an ovary with an entire or 2-lobed stigma. The fruits are 2-valved capsules.

Willows can be aggressive weeds along river banks and in wetlands.

The most common species are;

Salix alba (White Willow) is an erect tree to 20 m high with slightly drooping branchlets, finely toothed, narrow leaves which are 6-18 mm wide. The catkins are usually more than 25 mm long. Native to Europe and western Asia, it reproduces vegetatively and by seed.
Salix babylonica (Weeping Willow) is a deciduous tree to 20 m high with a stout trunk and has characteristic slender, drooping or weeping, green to brown-green branches and branchlets. The leaves are narrow, bright yellow-green l5-25 mm wide and terminate in a thread-like point. The flowers are in catkins usually less than 25 mm long in spring. It is rarely invasive but may hybridise with invasive Salix species. Native to eastern Asia it is widely cultivated and reproduces vegetatively.

Salix cinerea (Common Sallow Willow, Pussy Willow) is a rounded 1-2 m shrub or a multi-stemmed small tree to 10 m high with smooth grey-brown bark. The broader leaves, 15-40 mm wide, are shiny green on top and covered with soft grey hairs underneath. There flowers are in separate female and male catkins usually less than 25 mm long and they appear before the leaves in spring. It reproduces mainly by seed and is native to Europe and northern Africa.

Salix fragilis (Crack Willow) is a multi-stemmed tree up to 25 m high with dark-brown to grey deeply fissured bark and spreading rather than drooping branches. The branches make a cracking sound when broken. The broad leaves 10-30 mm wide are shining on the upper surface and hairless underneath. The catkins are long and slender, 60-80 mm long. it reproduces by seed but most infestations are usually male clones. It is native to Europe and Asia.

Salix nigra (Black Willow) is an erect, large shrub or tree to 20 m high with a single trunk which has dark to black-brown deeply fissure bark and narrow leaves with minutely toothed margins. The catkins have widely spaced flowers and individual trees are either male or female.

Salix x rubens (Basket Willow) is a spreading tree to 20 m high with several low branches and so appearing to be multi-stemmed. It has separate female and male individuals and the female catkins are long and drooping.

Salix viminalis (Common Osier) is a shrub or small tree to 6 m high, multi-stemmed with straight branchlets and with crowded, very slender leaves 4-8 mm wide which have silky hairs on the lower surface. The catkins are usually less than 25 mm long. It is native to Europe and northern Asia.

Cotyledons:

Two.

First leaves:

Leaves:

Deciduous in winter.
Stipules -
Petiole - less than 20 mm and less than one quarter as long as the lamina.
Blade - Long and narrow (except Pussy Willows) with finely toothed edges and usually paler on the underside.
Salix alba (White Willow)
Stipules -
Petiole - less than 20 mm and less than one quarter as long as the lamina.
Blade - Narrow, elliptic, 30-90 mm long by 6-18 mm wide. Edges finely toothed. Sparsely hairy on the upper side when young. Paler green on the underside and silky hairy and sometimes becoming hairless. Veins more prominent on the topside.
Salix babylonica (Weeping Willow)
Stipules - 5 mm long.
Petiole - 3-10 mm long.
Blade - 50-130 mm long by 5-25 mm wide. Shiny green on top and dull underneath. Edges often irregularly toothed
Salix cinerea (Common Sallow)
Stipules - tiny or to 5 mm long.
Petiole - 2-5 mm long.
Blade - Rounded to broadly lance shaped, 20-90 mm long by 15-40 mm wide with smooth or sometimes toothed edges. Shiny green on the upper surface sometimes with sparse hairs and covered with soft grey hairs on the underside. It rarely looses its hairiness with age. The leaves do not taste bitter.
Salix fragilis (Crack Willow)
Stipules - 3-6 mm long, toothed
Blade - Shiny green on top and lighter green underneath. Hairless. Lance shaped, 50-150 mm long by 10-30 mm wide, usually slightly curved with irregularly toothed edges. May be hairy when young but become hairless with age. The leaves often have red galls produced by the Willow Sawfly (Pontania proxima)
Salix nigra (Black Willow)
Blade - Lance shaped with minutely toothed edges and green topside is almost the same colour as the underside.
Salix viminalis (Common Osier)
Petiole - 2-5 mm long.
Blade - 40-90 mm long by 4-8 mm wide. Green and hairless on top, whitish and densely hairy below. Veins more prominent on the underside. Tip tapering to a point. Edges parallel and smooth. Base tapering.
Salix x rubens (Basket Willow)
Blade - Lance shaped with minutely toothed edges. May be hairy when young but become hairless with age.

Stems:

Salix alba (White Willow) Branchlets often drooping. Grey, fissured bark.
Salix babylonica (Weeping Willow) Drooping, smooth and hairless branchlets. Grey bark becoming deeply fissured with age. Up to 20 m tall.
Salix cinerea (Common Sallow) is multi-stemmed, erect to spreading and up to 10 metres tall but often only 1-2 metres tall with somewhat smooth, grey-brown bark. The branchlets are green to green-brown and often remain hairy in the cinerea (Grey Sallow) subspecies or dark red to brown and often become almost hairless in the oleifolia (Rusty Sallow) subspecies. The branchlets are not brittle.
Salix fragilis (Crack Willow) - Singled to multi-stemmed, up to 25 metres tall with erect and spreading branches and dark-brown to grey deeply fissured, rough bark. Branches often take root where they touch the ground. The branchlets dark-green to brown, upright, brittle and make a cracking sound when broken. Twigs diverge nearly at right angles
Salix x rubens (Basket Willow) 20-25 metres tall with spreading branches and green to orange or dark red, shiny branchlets.
Salix nigra (Black Willow) erect up to 20 metres tall with dark brown to black-brown deeply fissured bark. The branchlets are shiny, hairless and purple-brown.
Salix viminalis (Common Osier) Long, straight, flexible twigs that are grey and hairy when young.

Flower head:

Upright catkins carry many tiny flowers.
Male and female flowers occur on separate catkins or plants.
Salix alba (White Willow) Female ale catkins appear with the leaves and are 30-60 mm long.
Salix babylonica (Weeping Willow) Female catkins, 10-20 mm long appear with the leaves. Catkins elongate slightly when in fruit. Male plants not recorded in Australia.
Salix cinerea (Common Sallow) has separate male and female catkins that are cylindrical and are stalkless. Catkins appear before the leaves. Male catkins 15-35 mm long by 20 mm wide. Female catkins 20-40 mm long
Salix fragilis (Crack Willow) only produces male, cylindrical catkins, 40-75 mm long that spread or curve downwards. Catkins appear with the leaves.
Salix viminalis (Common Osier) Male catkins cylindrical, 20-30 mm long, stalkless and appear before the leaves.

Flowers:

Shrub Willows have black flower scales whereas tree Willows have pale scales.
Often fragrant
Ovary - Superior.
Perianth -
Stamens - 1-15
Anthers -
Salix cinerea (Common Sallow) has short densely hairy bracts.
Salix fragilis (Crack Willow) has elliptic to linear bracts.
Salix viminalis (Common Osier) has hairy bracts that are darker brown at the apex.

Fruit:

A two valved capsule containing many tiny seeds.
Salix alba (White Willow) stalkless.
Salix babylonica (Weeping Willow) Does not produce fruit in Australia because no male plants are here.
Salix cinerea (Common Sallow) Cylindrical, silky hairy.
Salix fragilis (Crack Willow) does not produce fruit as female plants are rare. (Capsule conical and shortly stalked overseas.)

Seeds:

Small with long silky hairs (pappus) attached to one end.

Roots:

Large, dense, woody, branching root mats are formed on the soil surface or in shallow, slow moving water.
Salix fragilis (Crack Willow) forms bright red rootlets when in or near water.

Key Characters:

Deciduous, dioecious tree.
Leaves alternate and with a petiole that is less than 20 mm and less than one quarter as long as the lamina.
Winter buds with a single outer scale.
Inflorescence a dense spike like catkin with greatly reduced flowers subtended by a scale-like bract.
Seeds small with a tuft of silky hairs.
Never forms suckers from roots.
Adapted from Gwen Harden

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