It generally has faster growth rates, attains a larger size and is tolerant to drier sites. These attributes suggest that this species has greater potential than other alders. Shape is variable depending on genetic type and environmental conditions. In dense stands, trees are self-pruning, leading to well formed smooth trunks. Flowers are borne in catkin-like structures with separate male and female inflorescences.
Fruit are similar to a miniature pine cone, shedding small, winged seed.
Trees have deep roots which establish a symbiotic relationship with Frankia or Actinomycetes alni actinomycetes. This symbiosis fixes nitrogen and allows phosphate to be made available in poor soils. The species has been in New Zealand since the late 1970s. Since 1989, more than 120 new accessions have been introduced, allowing for selection of better types. Because of the large range of genetic types available it is important to select those most appropriate to the required use.