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Taxa

Veronica

VerstrWrightsHill2010.jpgIntroduction

The largest adaptive radiation of plants in New Zealand is Veronica sect. Hebe, with over 120 species (Bayly & Kellow 2006; Wagstaff et al. 2002). This section of Veronica includes all the species previously classified as Hebe, Parahebe, Chionohebe, Leonohebe, Heliohebe, and Hebejeebie. A conspectus of all the species names can be downloaded from the attachments button at the bottom of this page (Garnock-Jones et al. 2007).

This change reflects the relationships of these New Zealand plants to northern hemisphere members of Veronica, a relationship clearly demonstrated by morphology, chemistry, cytology, and DNA sequence data. Many northern Veronica are more closely related to sect. Hebe than to other northern Veronica, so that treating the northern and southern species as belonging in separate genera would be misleading about these relationships.

Taxonomy

The species radiation began from a single ancestor perhaps 9 million years ago and the early branches of the radiation are alpine plants with Veronica-like features (Wagstaff et al. 2002). Several small clades radiated into distinct habitats at this time, and in the most recent molecular phylogeny of Veronica these are treated as informal groups (Albach & Meudt 2010). They include:

  • snow hebes (formerly Chionohebe and some Parahebe group B): alpine cushion- and mat-forming plants, with radially symmetric corollas and hygrochastic capsules. They are mostly found on high alpine rocks, but two species have independently switched to snowbank meltwater flushes. For taxonomy, see Meudt (2009) for the cushion plants, and Garnock-Jones & Lloyd (2004) for the subshrubs (also see next paragraph).

  • speedwell hebes (formerly Parahebe groups A & C): mostly lowland to montane subshrubs with striped short-tubed corollas and often toothed leaves. These are often found on rocky river and stream banks, but V. lilliputiana is a tiny creeping herb of lake and tarn margins, with blue flowers. A number of alpine species formerly classified in Parahebe group B are difficult to place and might belong here or be independent lineages, e.g., V. cheesemanii, V. zygantha. For taxonomy see Garnock-Jones & Lloyd (2004).

  • sun hebes (formerly Heliohebe): woody subshrubs with toothed leaves and terminal compound racemes, cream or yellow anthers, glandular-hairy nectar-disks, and elongated seeds. The species are found in NE South Island on lowland to alpine rocks. For taxonomy see Garnock-Jones (1993), but note that Veronica raoulii subsp. maccaskillii was raised to species rank, as Heliohebe maccaskillii, by Norton & Molloy (2009).

  • semiwhipcord hebes (formerly Leonohebe): small to large shrubs with scale-like leaves. Four of the five are alpine and plants are either male or female. They superficially look like whipcord hebes (part of the crown radiation below) but the leaf anatomy and DNA-based phylogeny show they have acquired this growth form independently. This group was treated taxonomically in Bayly & Kellow (2006).

  • hebes (formerly Hebe): The crown radiation of the shrubby hebes is much larger (about 90 species), and younger, perhaps 4 million years old. Most hebes are quite different from most northern Veronica: they are shrubby, with new leaves protected in an enlarged leaf-bud; leaves are generally entire, flowers mostly white with long corolla tubes, and fruits are flattened parallel to the septum and pointed. Nevertheless they retain similarities to northern Veronica, such as paired stamens, smooth flattened seeds, and similar flavonoid and iridoid chemistry. Most have 20 pairs of chromosomes or a multiple of 20. The species are mostly local to quite small regions in New Zealand, although about 20 are more widespread. DNA sequence data have not resolved the relationships within this group, although relationships within a few small clusters are well supported. Chromosome numbers and DNA sequnces support the view that the early offshoots in this radiation were small subshrubby plants with 21 pairs of chromosomes and toothed or crenate leaves. Hebe taxonomy was treated in detail by Bayly & Kellow (2006).

Biogeography

Veronica sect. Hebe is based in New Zealand and seems to have originated there, but some species have dispersed from New Zealand to other places (Wagstaff et al. 2002). Two snow hebes are also found in Australia ( V. densifolia in the Australian alps; V. ciliolata in Tasmania) and two shrubby hebes ( V. elliptica and V. salicifolia) have independently dispersed to South America. V. rapensis is found only on Rapa Island in French Polynesia, but it's very close to the Chatham Islands species such as V. dieffenbachii. Additionally there are about a dozen species in New Guinea that probably have a New Zealand ancestor. These are mostly speedwell hebes, but there is also the unusual V. tubata in its own group ( heath hebes), with large tubular deep blue flowers. Thus from a single ancestor, Veronica sect. Hebe has radiated widely in New Zealand and dispersed to neighboring lands.

References

Albach, Dirk C. & Heidi M. Meudt (2010) Phylogeny of Veronica in the Southern and Northern Hemispheres based on plastid, nuclear ribosomal and nuclear low-copy DNA. Molecular Phylogenetics and Evoluion 54: 457-471. Abstract

Bayly, Michael J. & Alison V. Kellow (2006) An illustrated guide to New Zealand Hebes. Te Papa Press, Wellington. Purchase here

Garnock-Jones, Phil J., Barbara G. Briggs & Dirk C. Albach (2007). Botanical names in Southern Hemisphere Veronica (Plantaginaceae): sect. Detzneria, sect. Hebe, and sect. Labiatoides. Taxon 56: 571-582. Abstract

Garnock-Jones, Phil J. & David G. Lloyd (2004) A taxonomic revision of Parahebe (Plantaginaceae) in New Zealand. New Zealand Journal of Botany 42: 181–232. Abstract

Garnock-Jones, Phil J. (1993) Heliohebe (Scrophulariaceae – Veroniceae) a new genus segregated from Hebe. New Zealand Journal of Botany 31: 323–339. Abstract

Meudt, Heidi M. (2009) Taxonomic revision of Australasian snow hebes ( Veronica, Plantaginaceae). Australian Systematic Botany 21: 387–421. Abstract

Norton, D.A. & B.P.A. Molloy (2009) Heliohebe maccaskillii (Plantaginaceae)—a new rank for a threatened limestone endemic, North Canterbury, New Zealand. New Zealand Journal of Botany 47:405–409. Abstract

Wagstaff, Steven J., Michael J. Bayly, Philip J. Garnock-Jones & Dirk C. Albach (2002) Classification, origin, and diversification of the New Zealand hebes (Scrophulariaceae). Annals of the Missouri Botanical Garden 89: 38-63. Abstract

Topic attachments
I Attachment Action Size Date Who Comment
JPEGjpg Verell_fl_500px.jpg manage 51.1 K 2012-09-12 - 09:26 PhilGarnockJones  
PDFpdf Veronica_conspectus_15Jan07.pdf manage 67.7 K 2010-05-27 - 06:59 PhilGarnockJones Translate names between the two treatments
Topic revision: r7 - 2012-09-12 - PhilGarnockJones
 
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