Alnus glutinosa


Alnus: From an old Latin name for alder
glutinosa: From the Greek gloeo 'glue', refers to the gummy leaves

Common Name(s)

common alder


Alnus glutinosa (L.) Gaertner



Brief Description

Widespread, especially common in the Waikato and Wairarapa, where it can be a problem weed.

Flora Category

Vascular - Exotic

NVS Species Code


The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.

Structural Class

Dicotyledonous Trees & Shrubs


Widespread, especially common in the Waikato and Wairarapa, where it can be a problem weed.


Riparian areas along rivers and lakes.


Tree to c. 15m high (to c. 20m in cultivation). Bark dark brown, strongly fissured. Young shoots glabrous but glandular-viscid. Winter buds shortstalked, purplish. Petiole 7-15 mm long, often purplish. Lamina 4-10 x 2.5-10cm (to 14 x 13cm on vigorous vegetative shoots), broadly oblong to obovate, plicate in bud, hairy on veins beneath at first, soon glabrous except for tufts axillary hairs, serrulate to coarsely serrate, lobulate on basal vegetative shoots; veins in 6-7 pairs, prominently raised beneath; base usually cuneate; apex rounded to retuse. Buds stipitate, not enclosing female catkins in winter. Male catkins 3-8 together behind shoot apices, 2.5-7cm long (to 12 cm in cultivation), cylindric, opening in spring before lvs; peduncles to c. 5 cm long; bracts peltate, purplish; anthers yellow. Female catkins 3-7 together behind shoot apices, c. 5mm long, glandular. Cone (1)-1.3-1.7-(2) cm long, ellipsoid; scales becoming horizontal after dehiscence and persistent on tree. Nutlet c. 3mm long, broadly ovoid; wing narrower than nut.

Similar Taxa

No similar tree in that habitat.


Late winter to spring

Flower Colours

Violet / Purple,Yellow



Year Naturalised



Europe, Asian and North Africa.

Reason for Introduction

Ornamental and timber tree also produces a yellow dye.

Control Techniques

Can be controlled mechanically or herbicidally depending on situation.

Life Cycle and Dispersal

Perennial. Wind and water dispersed seed, also forms thickets by suckering. Fruiting is prolific (Webb et. al., 1988).


The plant prefers moist a situation and has been planted in colder areas (Webb et. al., 1988).


Prepared by Paul Champion and Deborah Hofstra (NIWA). Features description and life cycle and dispersal and tolerances information from Webb et. al. (1988).

References and further reading

Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J. (1988). Flora of New Zealand Volume 4: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch.

Wikipedia - Alnus glutinosa

Popay et al (2010).  An illustrated guide to common weeds of New Zealand, third edition.  NZ Plant Protection Society Inc, 416pp.

Johnson PN, Brooke PA (1989).  Wetland plants in New Zealand.   DSIR Field Guide, DSIR Publishing, Wellington. 319pp.


This page last updated on 13 Nov 2013