Euphrasia petriei

Taxonomic notes

Flower-size varies greatly and can be used to divide the species into 2 more or less geographically separated forms:

In Canterbury and north-west Otago corollas are usually exceptionally large, (10-) 15-20 mm long and diameter, with lobes of lower lip 4-8 mm wide, bluntly expanded at tip and emarginate. Leaves are sometimes densely ciliate, and the plants may be up to 120 mm tall. This form (which includes the type) often occurs in company with E. revoluta sensu stricto and many mixed collections have been made. Even if the distinctive glandular pubescence is absent E. petriei is usually easily separated by its very differently shaped leaves, larger flowers, and stouter habit. However, occasionally specimens combine characters of both species and hybridism may be a factor contributing to the variability of E petriei in this part of its range.

In Fiordland and western Otago south of approximate latitude 44° corollas are much smaller, approximately 8-12 mm long and diameter, with lobes of lower lip only 2-4 mm wide and entire. Leaves are always glabrous and the plants rarely greater than 50 mm tall, though an anomalous collection from Clinton Saddle referred by Petrie to Euphrasia australis consists of luxuriant plants up to 100 mm tall with distant leaves and long pedicels. Dwarf densely tufted forms which have been collected on the Hector Mountains and Mount Pisa appear very distinct but are probably only epharmonic modifications. This form could receive varietal recognition, but as there is a possibility that Hooker’s Euphrasia antarctica var. major and/or var. grandiflora belong here no new epithet is given.