The Genus Lavandula

True story: I had just returned from the Algarve in mid-May when my copy of this book arrived.  We had visited many sites of wild lavender in Portugal, mainly L. stoechas subsp. luisieri and L. viridis, all in full flower.  In a lane just off the road to the Barragem de Santa Clara in the Baixa Alentejo, we came across hundreds of plants of L. stoechas subsp. luisieri and perhaps a few dozen L. viridis.  We noticed a different plant, just one – it was clearly a hybrid between the two species, with a viridis type flower head but with light violet corollas and pale purple-pink apical bracts.  The leaves were bright green and had a distinct viridis scent.  I can now tell you what that cross is called, as it appears in this book (p.255) as a rare hybrid - Lavandula alportelensis (below).

As we would expect from a Kew monograph, The Genus Lavandula represents a taxonomic overhaul, the first major revision of the genus since publication of Dorothy Chaytor’s paper in 1937, and is based on existing research and that carried out by the authors in the past 15 years or so.  The revised classification includes the introduction of three new subgenera (Lavandula, Fabricia and Sabaudia), an extra two sections on top of the existing six (Hasikenses and Sabaudia) together with recently and newly described wild species, resulting in an increase in their number from 32 to 39.  In addition, 24 more taxa are listed as subspecies, forms or varieties together with 16 new hybrids (eight from the wild and eight from cultivation).  Those two last rather dry sentences actually hide a most exciting and exhilarating read; give yourself lots of time.  Just to pull out a few plums at random:  L. pedunculata is now regarded as a species in its own right, rather than as a subspecies of L. stoechas.  Thank goodness we can all stop writing out L. stoechas subsp. pedunculata.  The variations of L. canariensis that appear on the seven major islands of the Canarian archipelago are noted and recognised now as seven subspecies, their names reflecting their geographical distribution.  My glee at losing L. stoechas subsp. pedunculata was short-lived faced with the prospect of writing out L. canariensis subsp. fuertaventurae, for example. Personally, I was not able to find any lavender on Fuertaventura and assumed it had all been grazed by goats decades ago.  A new species has been recognised from a small area of Gran Canaria and named for the Director of the Botanic Garden on that island, L. bramwellii.  I can see that I will just have to return to the Canaries for some more island hopping and lavender hunting.  Good.

In less accessible parts of the world, new species, we learn, are still being discovered and named.  For instance, from the Dhofar in Oman we have L. samhanensis and from the southern Yemen L. qishnensis.  Although, as

with some other lavender species from Arabia (and indeed Africa), they are unlikely to be garden worthy, they are of great interest botanically.  Existing species have also been reclassified: L. atriplicifolia, the yellow-brown flowered species from Saudi Arabia and the Yemen, comes in out of the cold and is joined by a newcomer from Eritrea, L. erythraeae, also with yellow-brown flowers, to form the new section Sabaudia within subgenus Sabaudia.

In addition to the descriptions of the individual species, other information includes distribution data (together with maps), notes on the flowering period and type of habitat together with a rating of conservation status.  Keys are provided for the subgenera, sections, species, subspecies and varieties.  The descriptions are accompanied by superb watercolours all detailing habit, flowering shoot, flower spike and an enlarged cyme (showing corolla, calyx and bract).  There are additional line drawings showing these features for some of the rarer species.  The three botanical illustrators who undertook the work won a well deserved Gold Medal for a selection of the paintings at the RHS Flower Show in London in February 2004.  Having seen the actual watercolours at this show, I feel that the quality of the reproductions in the book is slightly disappointing and does not do the original paintings full justice.  For instance, the foliage colour of L. dentata var. dentata and L viridis is more yellow than in the original watercolours. The 45 line drawings are presented in amazing detail (stem indumentum x 32 tells it all) – botanical drawings are of particular importance in highlighting the distinguishing characteristics of different species and these drawings must have taken many hours to prepare.

The history of lavender cultivation at the start of the book includes overviews of cultivation in different countries.  I learned a lot from the United Kingdom section, not least that Dorothy Chaytor died in her ninety-first year in 2003.  The Lavender Bag started in 1994 and had I known she was still alive (I drew a blank looking for any documentation about her since the publication of her monograph in 1937) I would have tried to interview her for a piece in one of the early issues.  There is an informative alphabetical tour around the UK’s past and present lavender farms, nurseries and major gardens where lavender was grown, followed by equally interesting overviews of lavender cultivation in France, North America, Australia, New Zealand, Japan and Africa.

Importantly, the book includes a comprehensive and long overdue treatment of the cultivated lavenders, the vast majority of which are from sections Lavandula and Stoechas.  The naming and descriptions of the hardy lavender cultivars has always been a minefield in the horticultural trade.  Nursery owners and gardeners alike will be grateful for the study and research that is reflected here.  Over 150 cultivars and field varieties of L. angustifolia are listed and described together with more than 70 lavandins, a feat which took Susyn Andrews around the UK, to France and over the world to New Zealand, Australia and North America in her quest for the origins and identities of the plants. These descriptions are supported with more of the watercolours and with photographs of flower heads and of lavenders growing in situ.  Clearly space did not allow for illustration of all the cultivars but the individual descriptions in the text are very detailed.  These include measurements of growth habit, peduncle length, leaf and spike size together with colour of bracts and bracteoles, calyx and corolla, the RHS colour chart quoted for the last two.  Even aroma is there, a challenge for anyone writing out verbal descriptions!  Where appropriate, degree of hardiness is commented on and if known, the history of the cultivar name is given.  In Appendix 8 part of the RHS Colour Chart is reproduced (the sections covering the red, purple, violet and blue groups) with standardised colour names given against the numbers.  I would never have believed there were so many measurable nuances in this colour range.  Another appendix is allocated to a historical overview of the white-flowered hardy lavenders.

Occasional questions are dropped in the text inviting comments from readers: “We have not seen live or dried specimens of ‘Grégoire’, ‘Maime Epis Tête’, ‘Spécial’ and ‘Standard’.  Do any, some or all resemble the long slender spiked lavandins that were grown in the 1940s-60s?” (p.180).

I found the account of the hybrids in Section Lavandula most interesting, particularly the cultivation history of the lavandins (pp 178 - 180).  It is obvious that an enormous amount of detective work has been undertaken, and judging by the number of pers.comm. attributions, much information has been obtained from discussions with individual nursery owners, collection holders, botanists and horticulturalists.  This shows too in the long listing (over 100) of cultivars of lavenders within section Stoechas.  Of these, 57 are hybrids involving L. stoechas or L pedunculata with L. viridis, prolific crosses usually occurring in warmer climates than here in the UK. 

A couple of crosses have now been accorded their own hybrid epithet.  Those between L. lanata and L. angustifolia can now be called

L. x chaytorae, in honour of Dorothy Chaytor, as in L. x chaytorae ‘Richard Gray’.  Since there are now about 15 such crosses, the convenience of a recognised name for such a plant is especially welcome.  And a lone lavender, the only known cross between L. lanata and L. dentata, is now named L. x ginginsii ‘Goodwin Creek Grey’ in honour of our old friend affectionately known among lavender lovers as Baron Fred, but more accurately called Baron Frédéric Gingins de la Sarraz, author of Histoire naturelle des Lavandes (1826).  We shall also have to get used to calling what we knew as L. x allardii either L. ‘African Pride’ (the plant with very few dentate leaves) or L. Anzac Pride’ (the one with mostly dentate leaves), both now placed as modern hybrid cultivars of unknown origin. 

The early chapters on cultivation, propagation and pests and diseases, to which Simon Charlesworth of Downderry Nursery has contributed, would make a handy little booklet for lavender growers in its own right.  I think the most frequently asked question wherever one goes is “When do I cut back my lavender?”  This, along with many other issues, is fully addressed here.  An overview of essential oil production and other commercial uses is provided by Brian Lawrence and Art Tucker. 

In their introduction, the authors state that they found many areas where further research would be desirable or their understanding is incomplete and they hope that publication of the monograph at this point will encourage further work on Lavandula.  Meanwhile, they have provided us with a feast and this significant publication demands a place on the bookshelves of absolutely anyone concerned with lavender.

 Reference Chaytor, D.A. (1937)  A taxonomic study of the genus Lavandula.    Journal of the Linnaean Society – Botany, 51:153-204

 --Joan Head, The Lavender Bag

Many thanks to Joan Head for her kind permission to reprint her comprehensive review of The Genus Lavandula. Joan compiles a wonderful booklet, The Lavender Bag, twice each year of all the latest in lavender happenings.

The Genus Lavandula ORDER
The Genus Lavandula
By Tim Upson and Susyn Andrews with illustrations by Georita Harriott, Christabel King and Joanna Langhorne

Hardcover  
422 pages 
The Royal Botanic Gardens, Kew, 2004

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