Hebe or Veronica?

Veronica pimeleoides flowers. Photo from the Hebe Society.

Hebes* are some of the iconic plants of New Zealand. New Zealand doesn't have a huge diversity of flora compared to some other parts of the world, but there are some groups of plants that have just gone ballistic, achieving incredible diversity, and New Zealand is home to more than a hundred hebe species. The botanist Armstrong commented in the late 1800s that the group was so diverse that New Zealand's flora would still be of interest even if the country's vegetation was solely composed of hebes (Metcalf, 2006). Their delicate inflorescences are a common sight in the field and in the garden. This Monday's taxon of the week is a hebe - Veronica pimeleoides subspecies pimeleoides.

*If there's anyone who hasn't encountered the word before, "hebe" is pronounced with two long 'e's - hee-bee.

Those of my readers who are familiar with hebes may have blinked a little there. Our conception of the place of hebes in the botanical world has changed a little in recent years. Not only has there been the transfer of hebes from the Scrophulariaceae to the Plantaginaceae* (Olmstead et al., 2001), there is the small matter of their generic allocation. During the 1800s and early 1900s, most of those New Zealand (and a few South American) species that would later become recognised as hebes were included in the genus Veronica, a genus originally established for an assortment of temperate Northern Hemisphere taxa. The genus name Hebe (after the Greek goddess of youth, the daughter of Zeus and Hera, wife of Heracles after his apotheosis, and the server of ambrosia at the gods' table) was originally established in 1789, but didn't really enter use until the 1920s (Albach et al., 2004). Even after the botanical community recognised the distinctiveness of Hebe, horticulturists still tended for some time to regard the hebes as Veronica (Metcalf, 2006). Over time, everyone seems to have adjusted to the new view, and some groups of 'Hebe' species were even committed to further segregate genera - Parahebe, Chionohebe and (ha ha) Hebejeebie.

*Olmstead et al. (2001) suggested that the family including Hebe be called Veronicaceae, but the Botanical Code requires the correct name to be Plantaginaceae.

Then along came Albach & Chase (2001), ready to shake things up again. As it turns out, Veronica minus Hebe is a paraphyletic assemblage. While zoologists tend to divide genera in such a situation, botanists are more likely to combine, and Hebe has reverted back to part of Veronica - specifically, Veronica subgenus Pseudoveronica section Hebe (Albach et al., 2004; Garnock-Jones et al., 2007). So far, the re-reallocation of hebe species does not seem to have gained a huge acceptance among the general public, so this is currently a work in progress.


Another view of Veronica pimeleoides (this silver-leaved variety seems to be the most popular in cultivation). Photo from here.

The species Veronica pimeleoides is native to the South Island of New Zealand, being found pretty much along the exact midline of the island from the Inland Kaikouras south to central Otago. There are two recognised subspecies, V. pimeleoides ssp. pimeleoides and 'Hebe' pimeleoides ssp. faucicola (Kellow et al., 2003). A form that has been known as Hebe pimeleoides var. glauca-caerulea is only known from cultivation and has never been confirmed in the wild state since its original collection, so is currently regarded as of uncertain status. The two recognised subspecies are mainly distinguished by their growth form and habitat. V. p. ssp. pimeleoides, which is found over most of the species' range, is a low, creeping shrub found near lakes and rivers (Kellow et al, 2003, describe it as growing to 30 cm in height, but Metcalf, 2006, describes it as rarely more than 5 cm tall). V. p. ssp. faucicola is found on rock faces in the southernmost part of the range in central Otago, and is a much taller plant growing up to 70 cm in height. Subspecies faucicola also tends to have lighter flowers than subspecies pimeleoides - the former has flowers that are mauve to pink, while the latter is blue to mauve. The chemical signature of the two subspecies is, as far as is known, indistinguishable, sucggesting that the two have only recently differentiated from each other (Kellow et al., 2003).

REFERENCES

Albach, D. C., & M. W. Chase. 2001. Paraphyly of Veronica (Veroniceae; Scrophulariaceae): evidence from the internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA. Journal of Plant Research 114 (1): 9-18.

Albach, D. C., M. M. Martínez-Ortega, M. A. Fischer & M. W. Chase. 2004. A new classification of the tribe Veroniceae - problems and a possible solution. Taxon 53 (2): 429-452.

Garnock-Jones, P., D. Albach & B. G. Briggs. 2007. Botanical names in Southern Hemisphere Veronica (Plantaginaceae): sect. Detzneria, sect. Hebe, and sect. Labiatoides. Taxon 56 (2): 571-582.

Kellow, A. V., M. J. Bayly, K. A. Mitchell, K. R. Markham & P. J. Garnock-Jones. 2003. Variation in morphology and flavonoid chemistry in Hebe pimeleoides (Scrophulariaceae), including a revised subspecific classification. New Zealand Journal of Botany 41: 233-253.

Metcalf, L. 2006. Hebes: A Guide to Species, Hybrids and Allied Genera. Timber Press.

Olmstead, R. G., C. W. de Pamphilis, A. D. Wolfe, N. D. Young, W. J. Elisons & P. A. Reeves. 2001. Disintegration of the Scrophulariaceae. American Journal of Botany 88(2): 348-361.