ARTICLE : Pseudopanax crassifolius and P. lessonii in Wellington

Pseudopanax crassifolius and P. lessonii in Wellington

Pseudopanax crassifolius and P. lessonii hybridise wherever they meet, producing a diverse array of morphological forms (see figure).   Pseudopanax crassifolius (horoeka, lancewood) occurs throughout New Zealand, but the natural distribution of P. lessonii (houpara, coastal five-finger) is restricted to the northern North Island (about Kawhia and East Cape northwards).   However, P. lessonii and derivative cultivars, as well as hybrids with P. crassifolius, have been widely planted, and have become naturalised (weedy) in many regions south of their natural distribution, including Wellington.

We are using DNA analyses to investigate the hybridisation between Pseudopanax crassifolius and P. lessonii.   Our focus is on determining the extent of geneflow amongst the species in northern populations, and the dynamics of these natural hybrid zones.   But we are also interested in what happens when naturalised P. lessonii populations meet indigenous P. crassifolius populations, as is the case around Wellington.   To this end, we would be grateful for reports of sizeable populations (say, 10 or more individuals) within the Wellington region of:
•   P. lessonii, its cultivars, and/or hybrids.
•   P. crassifolius, where there are mature adults, and particularly if P. lessonii, its cultivars, and/or hybrids occur nearby.

Any individual that looks like P. crassifolius but has at least some leaves with two or more leaflets is, we believe, actually a hybrid with P. lessonii.   Pseudopanax lessonii might be confused with the common P. arboreus (whauwhaupaku, five-finger) in having leaves with five or so leaflets.   However, P. arboreus has leaflets with distinct petiolules (i.e., the leaflets have prominent stalks), and the leaves have a sheathing stipule (i.e., the stalk bases of the leaves clasp the stem).   We believe that P. arboreus does not hybridise with either P. crassifolius or P. lessonii.   However, we would be delighted to hear from anyone with evidence to the contrary.

Leon Perrie and Lara Shepherd, leonp (at) tepapa.govt.nz, 04 381 7261, Te Papa, P.O. Box 467, Wellington

Pseudopanax crassifolius × P. lessonii (left) growing next to P. arboreus in bush at Stokes Valley.   Photo: Jeremy Rolfe.