T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Salix fragilis (Crack willow)

Kingdom:   Plantae
(unranked):        Angiosperms
(unranked):        Eudicots
(unranked):        Rosids
Order:       Malpighiales
Family:      Salicaceae
Genus:      Salix
Species:     S. fragilis
Binomial name: Salix fragilis
Synonym: Salix alba L. x S. euxina,
Common names: Crack willow, Brittle willow,

Salix fragilis is a medium-sized to large deciduous species of willow native to Europe and Western Asia. It is usually found growing beside rivers and streams and in marshes and damp areas.
S. fragilis has escaped cultivation to become an invasive species in various parts of the world. Here in New Zealand, it is widespread and often abundant.  it is listed on New Zealand’s National Pest Plant Accord, which means it cannot be sold or distributed. It can replace a habitat's native plant species diversity, by forming 'monoculture groves'. Usually, only the male plant is present in New Zealand so no fruit is formed unless hybridised. This species spread is facilitated by stem fragmentation and is then are carried via waterways and runoffs.
Salix fragilis is a medium-sized to large deciduous tree, which grows rapidly to 10–15 m tall, with a trunk up to 1 m diameter. It can be often multi-trunked. The tree's bark is dark grey-brown and can become coarsely fissured in older trees.
he lanceolate leaves are bright green, 9–15 cm long and 1.5–3 cm wide and have a finely serrated margin.
he catkins in New Zealand appear early spring are usually male (very rarely female) and can appear with or after leaves. Male catkins are 4-7.5cm long.

A multitrunked tree growing riverside Whanganui River.

Another tree in the same areas.

The  bright green leaves.

The leaves with a finely serrated margin.

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/