Illustrated Guide to New Zealand Hebes
By Michael Bayly and
Alison Kellow, published by Te Papa Press, PO Box 467, Wellington,
New Zealand, 2006, 388 pages, 28.5 × 20.5 cm, ISBN-13: 978-0-909010-12-6,
Review by Tony Hayter
The Hebe Society
his permission from
The New Zealand Garden Journal (Journal of the Royal New Zealand
Institute of Horticulture), Vol. 9, No. 2, December 2006, p. 27-29.
The September 2002 issue
of Hebe News carried an article by Mike Bayly describing
current research into the genus Hebe. This research aimed
to deliver a range of scientific papers, an interactive computer-based
key for the identification of species, and an illustrated guide.
The guide covers the
identification, classification and biology of Hebe and the
closely related genus Leonohebe. It describes 88 species
of naturally occurring Hebe and five of Leonohebe
(L. cheesemanii, L. ciliolata, L. cupressoides,
L. tetrasticha and L. tumida), but no horticultural
forms. Each plant is illustrated with between six and 13 colour
photographs; these show the whole plant, branchlet, leaf bud, leaf,
inflorescence, flower and capsule. The authors describe each plant
in detail including: habit, branches, leaf bud, leaves, inflorescences,
bracts, flowers, pedicels, calyx, stamens, ovaries, capsules and
seeds. The distribution and habitat are then given, followed by
notes on its relationship with other hebes. Finally the etymology
(origin of the name) is described.
The book is in three
parts: A - general chapters, B - identification, description and
nomenclature of each plant, and C - appendices, glossary, references
and an index.
In the Introduction the
authors point out that Hebe is New Zealand's largest genus,
and is particularly conspicuous in the subalpine and alpine regions.
Hebes occupy a wide range of habitats, from the coasts to the mountaintops,
and have a wide range of forms, from whipcords with tiny leaves
to large-leaved shrubs. Many of the species are similar in appearance,
and can be variable in form, which has given hebes a reputation
as a difficult group to study. It was thought that hybridisation
between species is common, but the authors point out that this has
been exaggerated, so that with care, and the use of a hand lens,
most plants can be identified.
The last complete survey
of Hebe was in the Flora of New Zealand, Volume 1,
1961. Research since that time has described further species, revealed
possible new taxa, and raised questions about the limits of known
species. The research project was planned to try to resolve these
questions, to undertake a biosystematic revision of the genus, and
to look at the evolution of the species. However in 1993 the paniculate
group (Hebe hulkeana, H. lavaudiana, and H. raoulii)
was given generic status as Heliohebe and is not included
in the book, which is a shortcoming. Eleven species have been described
since publication of the Flora, eight species are reinstated
(they were not regarded as such in the Flora), and five hebes
previously classified as species have been discarded.
The second chapter covers
the classification and evolution of Hebe and Leonohebe.
Previously Hebe had been placed in Scrophulariaceae, the
antirrhinum family; but recently the Angiosperm Phylogeny Group
regard it as a member of the Plantaginaceae, the plantain family.
The history of the discovery, description and classification of
Hebe species is given. From 1984 various authors have classified
Hebe based on evolution, at first using the form of each
species and latterly DNA derived data. This supports the idea that
Hebe is derived from Veronica; relationships within
Parahebe and Chionohebe are complex, with most hebes
descending from a common ancestor, although Hebe macrantha
is less closely related. The supposedly close relationship of Hebe
odora and the whipcord hebes is not supported, and the whipcords
fall into several groupings. The classification and naming of species
included in Veronica and Hebe is in a state of flux,
so further research is needed to resolve these problems. The classification
of species within Hebe is based on the Flora, although
a number of changes have been made based on recent but incomplete
The third chapter describes
distribution, habitats and biogeographic history of Hebe,
which occurs throughout New Zealand and its outlying islands. It
is found in most habitats (coastal, near-coast forests, lowland
wetland, riverside, cloud forest, beech forest, lakeshores, subalpine
scrub, grassland and rocky areas in subalpine to alpine regions),
although it is thinly distributed in forests. The number of species
in each area varies widely throughout New Zealand, with the maximum
number of species (25) in mountains at the borders of Nelson, Marlborough
and Canterbury. Here there is a wide range of habitats. Research
shows that Hebe arrived in New Zealand 1.5-5.5 million years
ago, probably in an alpine region; it formed new species in this
region and this was followed by a spread to lowland areas. Hebes
are able to colonise over long distances, and one species (Hebe
elliptica) extends to the Falkland Islands. The limited changes
in DNA confirm the recent origin of Hebe, but more research
is needed to pin down exact relationships within Hebe.
Phil Garnock-Jones has
contributed the fourth chapter, which examines the structure of
Hebe species. Hebes form an extensive system of fibrous roots,
which might explain why they rapidly exhaust the compost in pots.
Many hebes have a bushy habit, due to branching of the stems. These
often have noticeable nodes, i.e., where leaves have been attached.
Leaves have a decussate configuration; where opposite pairs of leaves
are at right angles to their neighbours. A large leaf bud is a common
feature. The leaf sinus, the gap between the bases of the terminal
pair of leaves, can be useful in identification, although it can
be present or absent within one species, e.g., Hebe pinguifolia.
Flowers are usually found as a simple lateral raceme. Other features
he discusses are: hairs, calices, corollas, androecium, pollen,
gynoecium, seeds, seedlings, juvenile forms, and flower development.
Ken Markham has written
the fifth chapter on flavonoids (leaf pigments) in Hebe.
Over 80 flavonoids have been found in Hebe, and each species
has its own (occasionally well-defined) flavonoid profile, giving
it the characteristics of a fingerprint. The profile varies within
each species, but this is much less than that displayed between
species. This analytical method has been used to explore the relationships
between species, and can be used to define hybrids and their parentage.
Chromosomes are the topic
covered by the authors in the sixth chapter, where there is a comprehensive
compendium of chromosome numbers for Hebe. The variation
of these throughout the genus is examined, and work to unravel the
ancestry of hebes is mentioned.
In the seventh chapter
Phil Garnock-Jones considers the reproductive biology of Hebe.
Some aspects have been studied, e.g., maintenance of gynodioecy
(some flowers having male and female reproductive organs, while
others have just female organs), breeding systems for Hebe stricta,
H. subalpina and H. strictissima, and seed shape.
However we have little knowledge of the breeding systems of most
species, their pollinators and development of flowers. Hebe flowers
are structurally similar, although there is a great diversity in
size and detail, but all lack the nectar guides of Parahebe.
The dominant flower colour is white, although some species have
strong colours, e.g., magenta in Hebe speciosa. Most hebes
flower in spring or early summer, with individual flowers lasting
from 2-5 weeks in Hebe strictissima and 2-3 days in H.
pinguifolia. Pollinators are a wide range of insects, although
H. speciosa is visited by birds.
In the eighth chapter
Peter de Lange describes the conservation status of Hebe.
Peter and co-workers have developed a system to classify the conservation
status of New Zealand native plants; this distinguishes between
plants that are under threat from human activities, and those that
are local or uncommon. Hebe is the largest genus in New Zealand,
but few are greatly at risk. 'Acutely Threatened' is the highest
risk category and this contains nine species of Hebe and
one of Leonohebe. Plants in this category are considered
management priorities. This category is further divided into three,
with the highest risk being 'Nationally Critical', in which are
included Hebe breviracemosa and H. societatis. The
former is an island endemic and the latter has apparently very local
distribution in penalpine (between alpine and subalpine) grassland.
Peter then outlines the risks facing hebes, many of which are of
very limited distribution.
The final chapter in
Part A is on cultivation. There is a summary of cultivation requirements,
a list of books on hebes, a mention of the Hebe Society and a photograph
of hebes for sale at a New Zealand garden centre.
Part B, the largest section
of the book, starts with a chapter on Material and Methods. Plants
were studied in the field, and as herbarium specimens and cultivated
plants (of known origin). The authors have arranged the species
into groups similar to those in the Flora, although with
significant differences. Within each group similar species are placed
together. Next there is a list of the characteristics. These are
used to describe each species and are: habit and form, branches,
leaves, juvenile leaves, inflorescences, flowers, pedicels, corolla,
stamens, nectarial disc, ovary and style, capsules and seeds.
Taxonomic Treatment gives
a synopsis of the eleven groups (nine for Hebe, two for Leonohebe)
used for identification. Each group is colour coded, and the distinguishing
features listed. In describing these groups I have given some of
the more well known examples in each.
The first group described
are the 'flagriformes' (whipcords). There is a key to the hebes
in this group, and then each plant is portrayed with a page of text
and a page of illustrations. There are nine species including Hebe
armstrongii, H. hectorii and H. ochracea.
The second group is the
'Connatae' (pairs of leaves are connate, joined at base). This group
has seven species including Hebe epacridea and H. haastii.
The third group is the
'Subcarnosae' (somewhat fleshy), which has dull, grey-green, waxy,
often fleshy leaves and usually no sinus. This group has seven species
including Hebe buchananii, H. gibbsii and H. pimeleoides.
The fourth group is the
'Occlusae' (closed, i.e., no sinus), which has glossy or dull, but
not usually glaucous, leaves (except in Hebe albicans, H.
glaucophylla and H. topiaria). There are 31 species,
and these include Hebe albicans, H. macrocarpa and
H. stricta. Here Hebe recurva has been included with
H. albicans, as recent research has shown that the latter
is very variable and no clear grounds could be found to separate
The fifth group is the
'Buxifoliatae' (box-leaved, a former name for Hebe odora).
The leaf sinus is shield shaped, each flower is directly attached,
i.e., no flower stalk). There are four species, and these include
Hebe odora and H. pauciramosa.
The sixth group is the
'Small-leaved Apertae' (conspicuous leaf sinus). The sinus is narrow;
the leaves are less than 4 cm long. There are 20 species and these
include Hebe diosmifolia, H. elliptica and H. venustula.
The seventh group is
the 'Large-leaved Apertae' (conspicuous leaf sinus). The sinus is
narrow; the leaves are greater than 4 cm long. There are eight species
and these include Hebe salicifolia and H. speciosa.
The eighth group is the
'Grandiflorae' (large flowers). The leaves have noticeable teeth.
There is one species, Hebe macrantha.
The ninth group is the
'Pauciflorae' (few flowers). This is a low-growing subshrub with
leaves narrowing to a conspicuous leaf stalk (petiole). There is
one species, Hebe pauciflora.
The tenth group is Leonohebe
section Leonohebe (semi-whipcords). The plants are low-growing
subshrubs, with leaves overlapping the stems. There are four species
and these include Leonohebe cheesemanii and L. tetrasticha.
These were formerly included in Hebe.
A chapter on nomenclature
follows. It considers the naming at all levels, from the genera
Hebe and Leonohebe, through species to possible wild
hybrids to horticultural forms. Finally there is a list of common
and Maori names.
Part C, Indices, has
an appendix which lists informal hebe names used by Audrey Eagle
in her books, and by A. P. Druce in two checklists. The second and
third appendices describe the variation in some characteristics
of Hebe hectorii and H. lycopodioides. The fourth
appendix illustrates the considerable variation in the size and
shape of the leaf outlines of 40 Hebe species. The fifth
appendix lists the sources of the plant specimens used in the photographs
of hebes and leonohebes. The book ends with a list of references,
a glossary and an index.
This is an excellent
book. The authors have succeeded in presenting a huge quantity of
data which shows the current understanding of Hebe and Leonohebe.
The language used is of necessity technical, but the glossary helps
the attempts of an amateur botanist like me to understand it. The
quality of the text, layout and photographs throughout is very high.
version of this review is also published in Hebe News,
2006, Vol. 21, No. 4.
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