The Cordia Clade

The tropics are home to a wide diversity of plant species, many of them belonging to groups less familiar in cooler regions of the world. Prominent among these are members of the family Cordiaceae, a group of about 350 known species of mostly trees and shrubs. The Cordiaceae (alternatively treated as the subfamily Cordioideae of the family Boraginaceae) are a well distinguished clade both molecularly and morphologically. Most members of the clade have flowers with the stigma divided between four lobes, fruits with an undivided endocarp, and plicate cotyledons (Miller & Gottschling 2007).

Beach cordia Cordia subcordata, copyright Tauʻolunga.

Historically, most members of the clade have been assigned to a single genus, Cordia. This arrangement was revised by Miller & Gottschling (2007) who recognised the separate genus Varronia for about 100 species of multi-stemmed shrubs native to the New World. The remaining 250 or so species, most of them single-trunked trees, remained in the pantropical Cordia. The two genera also generally differ in their leaves (most Varronia have leaves with serrate margins whereas Cordia have entire margins) and inflorescences (most Cordia have broad cymose inflorescences whereas Varronia have smaller, more compact inflorescences). Few species of Cordiaceae are not assigned to either Cordia or Varronia. Three previously recognised small genera, Auxemma, Patagonula and Saccellium, are now synonymised with Cordia. The small African genus Hoplestigma and the prostrate annual herb Coldenia procumbens are placed in Cordiaceae primarily on the basis of molecular data (Miller & Gottschling 2007; Weigend et al. 2014).

Black sage Varronia curassavica, copyright Mauricio Mercadante.

A number of Cordia species are grown for their wood, with South American species providing timbers known as bocote, freijo (C. alliodora), and ziricote (C. dodecandra). These are only moderately strong woods but strikingly patterned and are more often used for aesthetic rather than structural purposes (such as cabinet veneers and musical instruments). Cordia alliodora has become an invasive in regions where it has been planted outside its native range such as Africa and Vanuatu. Various species are also grown for their edible fruits, such as the Assyrian plum C. myxa and the fragrant manjack C. dichotoma. These fruits are decidedly gooey when ripe and are often given names reflecting this fact such as glue berries, clammy cherries or, here in Australia, snotty gobbles (though this name is more widely used for fruits of the unrelated genus Persoonia). Pulp from unripe fruits of C. myxa can supposedly also be used as a type of glue. Your office reports may not be informative but they will at least be tasty!

REFERENCES

Miller, J. S., & M. Gottschling. 2007. Generic classification in the Cordiaceae (Boraginales): resurrection of the genus Varronia P. Br. Taxon 56 (1): 163–169.

Weigend, M., F. Luebert, M. Gottschling, T. L. P. Couvreur, H. H. Hilger & J. S. Miller. 2014. From capsules to nutlets—phylogenetic relationships in the Boraginales. Cladistics 30: 508–518.

The New Centaury

In an earlier post, I described the South American flowering herbs known as the Coutoubeinae. In this post, I'm going to take a step back and look at a clade of which the coutoubeines form a part, the Chironieae.

Seaside centaury Centaurium littorale, copyright Anne Burgess.

The Chironieae are one of the major tribes of the flowering plant family Gentianaceae, including about 160 known species. Representatives are found in most parts of the world, though as part of the native flora in Australasia they do not extend past the north of Australia (some exotic species have been introduced further south). The Chironieae seem to primarily be supported as a clade on the basis of molecular data (Struwe et al. 2002). All members are herbs, from annuals to short-lived perennials. Most have an erect growing habit; members of the Caribbean genus Bisgoeppertia are annual climbers and some species of the Mexican genus Geniostemon are creeping perennials. There may or may not be a basal rosette of leaves, and a number of genera have winged stems. Flowers are solitary or borne in cymose or racemose inflorescences. These flowers are most commonly salver-shaped (that is, shaped like a flat dish) or tubular, and usually have four or five petals (some species may have up to twelve). The calyx is usually comprised of fused sepals and is unwinged and tubular. The fruit is usually a septicidal capsule (splitting along the septa between carpels), more rarely a berry.

Yellow centaury Cicendia filiformis, copyright Hajotthu.

Members of the Chironieae are divided between three subtribes that are mostly distinct both morphologically and biogeographically. As described in the previous post, the Neotropical Coutoubeinae are characterised by releasing their pollen in tetrads whereas the other subtribes shed individual pollen grains. The Canscorinae are mostly found in the Old World tropics and have white or cream-coloured flowers (less commonly yellow, pink or purple) with the calyx tube longer than the calyx lobes. The Chironiinae mostly includes found in northern temperate regions, as well as the southern African genera Chironia and probably the South American Zygostigma. Their flowers come in a range of colours—pink, yellow, purple or blue, but less commonly white or cream-coloured—and may have calyx lobes longer than the tube. Many chironiine flowers also have anthers that become spirally twisted after releasing pollen whereas those of Canscorinae are always straight. Molecular data usually support the monophyly of the three subtribes and the majority view seems to be that the temperate Chironiinae represent the sister group of a tropical clade of Canscorinae and Coutoubeinae.

Cultivated Eustoma, copyright Rameshng.

Perhaps the best known members of the Chironieae are the centauries of the genus Centaurium. Historically, about fifty species across the Holarctic have been included in this genus. However, phylogenetic studies have demonstrated that this broad sense of the genus is polyphyletic and thus it has been cut down to a group of about twenty species found in Europe and western Asia. The name 'centaury' refers to the use of common centaury Centaurium erythraea as a medicinal herb, after the legendary centaur healer Chiron. Other Old World species are now placed in the genus Schenkia whereas North American species form the genera Gyrandra and Zeltnera. The yellow centauries of Cicendia are small, filiform annuals native to Europe and the Americas that have been introduced to Australia. The rose gentians Sabatia of North America bear pinkish-purple flowers, often in lax cymes. There are also the prairie gentians of the genus Eustoma. Native to southern North America, these plants bear large, showy flowers that have become popular in cultivation. Commercially, they are labelled as lisianthus. This is not to confused with Lisianthius, a distinct genus of Gentianaceae, or Lisyanthus, a name that has been used in the past for members of yet another gentianaceous genus. Both of these belong to completely different tribes in the family, and may be subjects for another day.

REFERENCE

Struwe, L., J. W. Kadereit, J. Klackenberg, S. Nilsson, M. Thiv, K. B. von Hagen & V. A. Albert. 2002. Systematics, character evolution, and biogeography of Gentianaceae, including a new tribal and subtribal classification. In: Struwe, L., & V. A. Albert (eds) Gentianaceae: Systematics and Natural History pp. 21–309. Cambridge University Press: Cambridge.

The Coutoubeines

Members of the family Gentianaceae, the gentians, are for the greater part associated with cooler climes. Residents of areas subject to heavy snowfalls have often commented on the appearance of their showy flowers with warming weather in the spring. But not all subgroups of the gentians are so temperate: some, such as the Coutoubeinae, are inhabitants of the tropics.

Schultesia guianensis, copyright João de Deus Medeiros.

The Coutoubeinae are a group of about thirty known species divided between five genera found in Central and South America (Struwe et al. 2002). A single species, Schultesia stenophylla, is found in western Africa but, as it is also found in Brazil alongside related species, it can be reasonably presumed to be a recent immigrant to that region. Like most other members of the Gentianaceae, species of the Coutoubeinae are low herbs, often found growing in open habitats. With the exception of the genus Deianira, most lack a basal rosette of leaves. Flowers are usually white or pink, and are quadrimerous (with four corolla lobes) in the majority of species (one species, Schultesia pachyphylla, has blue pentamerous flowers; Guimarães et al. 2013). Perhaps the most characteristic feature of the group is that pollen is released in tetrads (clumps of four). I haven't come across any specific comments on the functional significance (if any) of this feature in coutoubeines but it has been suggested that pollen clumping in plants may correlate with visits from pollinators being relatively uncommon (and getting a decent amount of pollen transported at a time becomes more important than increasing the chance of pollen being transported to multiple targets).

Coutoubea spicata, copyright Alex Popovkin.

The largest genus of coutoubeines is Schultesia, including about twenty species. Schultesia species are annual herbs with long-lanceolate leaves and tube-shaped, usually pink (occasionally yellow or blue) flowers with the calyx tube at least as long as the lanceolate corolla lobes. The species Xestaea lisianthoides, sometimes included in Schultesia, differs from Schultesia in the arrangement of stamens (inserted unevenly in the corolla rather than in the upper part of the tube) and the shape of the stigmatic lobes (oblong rather than rounded). Coutoubea species have white, salver-shaped flowers with triangular corolla lobes. Symphyllophyton caprifolium, a rare species restricted to southern Brazil, is a short-lived perennial with perfoliate leaves and yellow to cream salver-shaped flowers with the calyx tube shorter than the corolla lobes. Finally, Deianira includes suffrutescent herbs with a basal rosette of leaves and salver-shaped flowers with a short calyx tube.

REFERENCES

Guimarães, E. F., V. C. Dalvi & A. A. Azevedo. 2013. Morphoanatomy of Schultesia pachyphylla (Gentianaceae): a discordant pattern in the genus. Botany 91: 830–839.

Struwe, L., J. W. Kadereit, J. Klackenberg, S. Nilsson, M. Thiv, K. B. von Hagen & V. A. Albert. 2002. Systematics, character evolution, and biogeography of Gentianaceae, including a new tribal and subtribal classification. In: Struwe, L., & V. A. Albert (eds) Gentianaceae: Systematics and Natural History pp. 21–309. Cambridge University Press: Cambridge.

Sending Forget-me-nots

The Chatham Islands forget-me-not Myosotidium hortensia, from here.

I haven't been able to prepare a full post lately as we're currently in the field conducting our next survey round for the day job. In the meantime, I'll just content myself with a brief introducion to the Cynoglosseae. This is a tribe in the plant family Boraginaceae, redefined by Långström & Chase (2002) on the basis of molecular phylogeny to effectively correspond to the clade of Boraginaceae with heterocolpate pollen, as well as an undivided style with a single stigma (another tribe of Boraginaceae, the Boragineae, was covered in an earlier post). In the heterocolpate pollen of Cynoglosseae, the three apertures found in the pollen of other Boraginaceae alternate with an equal number of 'pseudoapertures'. The pseudoapertures represent gaps in the outer exine coat of the pollen grain like the apertures, but lack certain other features of the latter such as a concentration of cytoplasmic vesicles, as well as being longer and narrower (Hargrove & Simpson 2003).

Flower of camelbush Trichodesma zeyanicum, photographed by Ethel Aardvark.

Perhaps the most familiar members of this usage of Cynoglosseae are the forget-me-nots of the genus Myosotis, with other members including the hound's-tongue Cynoglossum officinale and, here in Australia, the camelbush Trichodesma zeylanicum. Offhand, camelbushes are generally one of the more prominent flowering plants here on Barrow Island, my current location, though they're one a bit of a low right now. There has been a bit of rain, and camelbush doesn't like to get its feet wet.

The traditional associations of forget-me-nots, of course, are right there in their name. There are a number of stories supposedly explaining how these flowers came to be associated with the memory of loved ones (surely the most ridiculous being the one that apparently has a knight drowning under the weight of a bouquet of the things) but the true reasons are probably lost to history. My own suspicion is that it is perhaps ultimately because forget-me-nots are relatively unassuming as flowers go, making them an ideal symbol of beauty that should not be overlooked for the sake of more flashy but perhaps less reliable competitors.

Hound's-tongue Cynoglossum officinale, from here. Native to Europe, this plant has become established in many parts of North America.

Hound's-tongue, on the other hand, seems to get its name from the resemblance of its leaves to its namesake. This plant doesn't seem to have quite the same hold on human affection as the forget-me-not, and the reason for this may be indicated by some of its other vernacular names: 'monk's nit' or 'beggar's lice', in reference to its sticky seeds that adhere to clothing (perhaps 'gypsy flower' derives from the same source?) and, even more damning, 'rats and mice', referring to its unmistakeable smell.

REFERENCES

Hargrove, L., & M. G. Simpson. 2003. Ultrastructure of heterocolpate pollen in Cryptantha (Boraginaceae). International Journal of Plant Sciences 164 (1): 137-151.

Långström, E., & M. W. Chase. 2002. Tribes of Boraginoideae (Boraginaceae) and placement of Antiphytum, Echiochilon, Ogastemma and Sericostoma: a phylogenetic analysis based on atpB plastid DNA sequence data. Plant Systematics and Evolution 234: 137-153.

Borage and Comfrey and Bugloss

Anchusa undulata ssp. granatensis. Photo by James Gaither.

The tribe Boragineae includes about 170 species of herbaceous flowering plants, mostly found in the Palaearctic region with only a couple of species extending into southern Africa. The group is well-distinguished by the presence of what are called fornices, the whitish lobes at the base of each petal that you can see in the photo above, as well as features of their seeds. Many Boragineae seeds have an elaiosome, a fatty plug at one end that attracts foraging ants (Hilger et al., 2004). The ants carry the seed back to their nest as food, but the plant produces enough seeds that at least some will not be eaten but will be able to germinate after being carried under the ground and away from anything else that might eat them.


Abraham-Isaac-Jacob, Trachystemon orientalis, a native of forests around the Black Sea and one of the more unusual species of Boragineae. Apparently the unusual name refers to the flowers changing colour as they age. Photo by Daniel Mosquin.

The species are divided between about fifteen genera (the exact number varies depending on whom you ask). The largest generally-recognised genus, Anchusa (the buglosses), was identified by Hilger et al. (2004) as para-/polyphyletic with a number of smaller genera also nested within the Anchusa clade, suggesting that the currently recognised constituent subgenera may need to be recognised as separate subgenera (or else the genera Lycopsis and Cynoglottis submerged into Anchusa). Other relationships within the tribe recognised by this and other studies include a close relationship between the genera Borago (borage) and Symphytum (comfrey), and between Nonea and Pulmonaria (lungwort). The basalmost member of the tribe is Pentaglottis sempervirens, which is also the only member of the tribe found in the Atlantic region of southwest Europe. The relict distribution of this species, as well as the concentration of diversity for the tribe overall, have been cited as supporting a Mediterranean origin for the Boragineae.


Green alkanet, Pentaglottis sempervirens, the sister species to all other Boragineae. Photo by Carl Farmer.

A number of members of the tribe have long been cultivated and many are even labelled by their botanical names as officinal (the Medieval Latin term 'officinalis' refers to a plant or substance that is kept in an apothecary; not surprisingly, many plants with supposed medicinal values are also eaten for their nutritional values). Borago officinalis, borage, is used as a salad or pot herb in Europe. Symphytum officinale, comfrey, has also been widely used medicinally, mainly for external uses such as soothing bruises (some of the properties attributed to comfrey verge on the ridiculous: a bath steeped in comfrey was supposedly able to restore a woman's virginity). Pulmonaria officinalis, lungwort, received its name because of the supposed resemblance of its blotchy leaves to lung tissue. Under the unabashedly loopy herbalist principle known as the Doctrine of Signatures, this outward resemblance indicated its suitability in treating lung diseases such as tuberculosis (in fact, lungwort contains toxic alkaloids that make it dangerous to take internally).

REFERENCES

Hilger, H. H., F. Selvi, A. Papini & M. Bigazzi. 2004. Molecular systematics of Boraginaceae tribe Boragineae based on ITS1 and trnL sequences, with special reference to Anchusa s.l. Annals of Botany 94 (2): 201-212.

My Flower is a Trumpet (Taxon of the Week: Solanales)

Fruit of Physalis alkekengi var. franchetii, the Chinese lantern plant. In species of Physalis, the persistent calyx that is characteristic of Solanales has become greatly expanded to form a protective covering for the (rather tasty!) fruit. Photo from here.

While intrafamilial relationships among flowering plants have a reputation for being contentious, one concept that has long been supported by most authors is a close connection between the Solanaceae (nightshades) and the Convolvulaceae (morning glories). Originally united on the basis of features such as similar flower structure and internal phloem in most species (the phloem is the nutrient-carrying tissue in a plant's stem, and in these taxa it is found mixed in with the central water-carrying xylem as well as around the outside of the stem as in other plants), molecular analyses have continued to support their relationship (Bremer et al., 2001). In the most recent APG classification, the two families form the greater part of the order Solanales, along with three smaller families - Montiniaceae (a family of trees and shrubs found in southern Africa and Madagascar) and the isolated genera Sphenoclea and Hydrolea (two pantropical families of small shrubby plants both found growing near or in water) (APG II, 2003).


Montinia caryophyllacea, a shrub of the Montiniaceae found from South Africa to Angola. Photo from Aluka.

The three small families, which remain outside the Solanaceae-Convolvulaceae clade (which I'll call the "core Solanales"), are placed in the Solanales largely on the basis of molecular analyses only, and so far few or no morphological features have been identified that support their referral. Peter Stevens' Angiosperm Phylogeny Website does suggest a couple of features - some shared secondary metabolites, and the fact that the calyx persists on the mature fruit (you've all seen this - it's the sepals around the stalk of a tomato). Erbar et al. (2005) identified features of flower development shared between Hydrolea and the core Solanales, but not the other two families. Most Solanales are, like other members of the Asteridae clade to which they belong, sympetalous - that is, the petals are to some degree joined together at their base. One of the distinctive features of many Convolvulaceae and Solanaceae flowers, in fact, is that they take sympetaly to its extreme - the petals are entirely fused to form a bowl or trumpet. However, while the core Solanales and Hydrolea are "late sympetalous", where the petals initially start growing separately in the bud and are only joined later by the growth of connecting bridges, Sphenoclea is "early sympetalous", where the petals are connected pretty much right from the start. Montiniaceae are not sympetalous at all, but have entirely separated (and not very big) petals.


Kumara or sweet potato, Ipomoea batatas. Photo from here.

Within the core Solanales, the Convolvulaceae are mostly vines (though the basalmost member of the Convolvulaceae, Humbertia madagascariensis, is a large tree), while the Solanaceae range from small herbaceous plants to large trees. As well as being a tree, Humbertia also differs from other Convolvulaceae in lacking internal phloem. This is intriguing, because Humbertia's sister relationship to all other Convolvulaceae means that it is just as parsimonious for internal phloem to have developed independently in the two families as for it to be a true synapomorphy of the core Solanales. The herbaceous vines of the Convolvulaceae are commonly referred to as morning glories, referring to the time of opening of their large but often short-lived flowers, but other common names are just as evocative - trumpet vine, or railway creeper (the latter because many species have become widely distributed as adventives inadvertently carried by human activity). They are also, somewhat less poetically, known as bindweeds. One such plant, Ipomoea batatas, grows large tubers that are the world's second-most important root crop, the sweet potato (Stefanović et al., 2002).


Dodder, Cuscuta epithymum, overgrowing a sage plant. Photo from Kingston University.

One particularly distinctive genus of Convolvulaceae are the dodders, Cuscuta, twining parasites of other plants. Dodders contain little or no chlorophyll of their own, and their roots degenerate early on in life so the mature plant is not connected to the ground. The leaves are minute, and one might be forgiven for thinking that they were not there at all. Cuscuta has been placed in its own family in the past, but most of the characters this has been based on are uniquely derived features resulting from its parasitic lifestyle. Neyland (2001) and Stefanović et al. (2002) confirmed that Cuscuta is nested among normal photosynthetic Convolvulaceae. Cuscuta also provides a remarkable example of convergent evolution - in its general appearance, it is almost indistinguishable from the genus Cassytha, also commonly called "dodder". Cassytha, however, is not closely related to Cuscuta at all, but is instead a member of the distant family Lauraceae, and so more closely related to magnolias.

The Solanaceae also include a number of significant taxa. As a group, most Solanaceae are decidedly toxic (at least from a human perspective), and the family includes such infamous plants as deadly nightshade (Atropa belladonna), Jerusalem cherry* (Solanum pseudocapsicum) and Jimson weed (Datura stramonium). On the other hand, the family also includes a number of plants widely grown for human consumption, such as potatoes (Solanum tuberosum), tomatoes (Solanum lycopersicum**) and eggplants (Solanum melongena). A few Solanaceae manage to be both toxic and grown for human consumption - most notably good old tobacco (Nicotiana tabacum). The question arose recently at the Te Papa blog as to whether the common black nightshade (Solanum nigrum) is toxic or not - while it is widely supposed to be, it is actually eaten in some parts of the world (Edmonds & Chweya, 1997). Fruit are eaten when ripe or cooked (the huckleberry of North America is either Solanum nigrum or a close relative), while leaves are boiled and eaten as a pot herb. It seems that, just to confuse matters, toxicity of this plant varies from place to place.

*No, I don't know why they're calledd that.

**For those who are wondering what happened to 'Lycopersicon esculentum', it has been well established that 'Lycopersicon' species fall phylogenetically within Solanum (as Solanum section Lycopersicum), and in fact are very closely related to potatoes (somatic hybrids between potatoes and tomatoes have been succesfully produced, though it looks like produce-wise they're a bit of a second Raphanobrassica***). If the tomato is included in Solanum, then its name reverts back to that originally given to it by Linnaeus way back in 1753.

***Raphanus (radishes) and Brassica (cabbages) are also closely related to each other, and a lot of time and effort was invested by the early Soviets into producing a hybrid between the two that would possess the root of a radish with the leaves of a cabbage - two crops for the price of one! The Raphanobrassica cross was successfully produced in the 1920s - sadly, it turned out to have the root of a cabbage and the leaves of a radish.

REFERENCES

APG II (Angiosperm Phylogeny Group). 2003. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG II. Botanical Journal of the Linnean Society 141: 399-436.

Bremer, K., A. Backlund, B. Sennblad, U. Swenson, K. Andreasen, M. Hjertson, J. Lundberg, M. Backlund & B. Bremer. 2001. A phylogenetic analysis of 100+ genera and 50+ families of euasterids based on morphological and molecular data with notes on possible higher level morphological synapomorphies. Plant Systematics and Evolution 229: 137-169.

Edmonds, J. M., & J. A. Chweya. 1997. Black nightshades. Solanum nigrum L. and related species. Promoting the conservation and use of underutilized and neglected crops 15. Institute of Plant Genetics and Crop Plant Research, Gatersleben/International Plant Genetic Resources Institute, Rome, Italy.

Erbar, C., S. Porembski & P. Leins. 2005. Contributions to the systematic position of Hydrolea (Hydroleaceae) based on floral development. Plant Systematics and Evolution 252: 71-83.

Neyland, R. 2001. A phylogeny inferred from large ribosomal subunit (26S) rDNA sequences suggests that Cuscuta is a derived member of Convolvulaceae. Brittonia 53 (1): 108-115.

Stefanović, S., L. Krueger & R. G. Olmstead. 2002. Monophyly of the Convolvulaceae and circumscription of their major lineages based on DNA sequences of multiple chloroplast loci. American Journal of Botany 89 (9): 1510-1522.

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.