Section 4 Pterostoechas Ging

Woody based perennials or woody shrubs with pinnatisect to bipinnatisect leaves with distinct petioles. Bracts on axis of spike arranged in an opposite and decussate manner, subtending a single-flower with no bracteoles, giving a four-seriate (quadrate) spike. Subtending bracts ovate lanceolate in shape, with parallel veins. Calyx fifteen-nerved, bilobed the median posterior tooth often distinctly deltoid, the other lanceolate in shape. Corolla bisymmetrical, twice the length of the calyx, five-lobed, the upper two erect and twice as large as the three lateral lobes. Stigma bilobed. Nutlets elliptic, the lateral scar one-third the length of the nutlet, mucilaginous. The important characters for distinguishing the species include leaf shape, indumentum, length of the bract subtending each flower and the shape of the upper middle lobe of the calyx.

The largest section in the genus with at least thirteen species, distributed from the Canary Islands, Cape Verde Islands, Madeira, across North Africa, parts of the Mediterranean basin, the southern Arabian Peninsula and reaching Iran.

1 Median upper calyx lobe narrowly triangular in shape and ± equal in size and shape to the other lobes L. coronopifolia

Median upper calyx lobe deltoid in shape, differing in size and shape to all other lobes 2

2 Whole plant with a silver grey indumentum 3

Plants glabrous or with a sparse to dense indumentum of glandular and/or non-glandular hairs 4

3 Plant a low-growing shrub 20—40 cm. Bracts large, ovate in outline,

1.5 X length of the calyx. Canary Islands and Madeira L. pinnata

Plant a robust shrub 50-100 cm. Bracts lanceolate to ovate/lanceolate in outline, 0.5-0.75 X length of the calyx. Canary Islands (Tenerife) L. buchii

4 Stems glabrous to glabrescent or very sparsely tomentose 5

Stems with a distinct indumentum of either short hooked stiff hairs, long white stiff hairs, highly branched hairs, or short stalked glandular hairs or combination thereof . . . 7

5 Leaves pinnatisect to bipinnatisect. Leaves not fleshy 6

Leaves irregularly dissected, lobed or dentate. Leaves fleshy L. rotundifolia

6 Plants woody at the base only, stems herbaceous. Bracts with membraneous wings, orbicular-pentagonal in shape L. maroccana

Plants with woody stems, only the seasons growth herbaceous. Bracts without wings, ovate in shape L. canariensis

7 Stem indumentum of short branched and long white stiff hairs, present at least on the lower stem. Spike with a distinct twist L. multifida

Stem indumentum of large branched hairs, short stalked glandular hairs and/or stiff white non-glandular hairs or combination thereof. Spike not twisted 8

8 Stems grey-green indumentum of large branched hairs. Leaves with deep very regular pinnatisect divisions L. minutolii

Stems with an indumentum of short stiff hairs, long white stiff hairs and/or short stalked glandular hairs 9

9 Stem indumentum of short stiff hairs often hooked, with long stiff hairs. Glandular hairs few. Bracts ovate with a long acuminate tip with three main nerves 10

Stem indumentum of short stalked glandular hairs over white stiff hairs. Bracts ovate lanceolate usually with five main nerves 11

10 Stem indumentum of short hooked stiff hairs, with occasional long stiff hairs and short stalked glandular hairs. Algeria and Niger L. antineae

Stem indumentum of short stiff simple hairs often interspersed with longer stiff hairs. Glandular hairs absent. Morocco L. tenuisecta

11 Bracts at least the length of the calyx or exceeding it in length (1-1.5x) L. mairei

Bracts 0.6-1 X length of calyx 12

12 Leaves distinctly 2-3 pinnatisect (lobed to midrib). Plant highly aromatic, rather unpleasant aroma L. pubescens

Leaves principally pinnatifid (lobed to only half the distance to midrib).

Plant aromatic with distinct smell of lemons L. citriodora

Figure 2.11 L. multifida - close up showing flower spike, Morocco near Oued Laou. (See Color Plate VI.)

Perennial with woody base to 40 cm. Leaves 3-6 cm, deeply dissected pinnatisect to bipinnati-sect. Stems with diagnostic short branched hairs and long white simple hairs (sometimes only present near base). Inflorescence stalk usually branched at the base, flower spike 5-8 cm, twisted. Bract elliptic with sharply acute apex, typically with three dark nerves, ± to equal length of calyx. Upper middle lobe of calyx distinctly deltoid in shape. Corolla bicoloured, the lower lobes violet fading to blue-violet on the upper lobes with darker guidelines. Native to South Spain, Italy (Southern tip only), North Africa (Morocco, Algeria, Tunisia and Libya) often associated with open disturbed areas and areas of habitation. Occasionally cultivated as an ornamental, usually treated as an annual.

8. L. canariensis Mill. (L. abrotanoides Lam.; L. multifida L. subsp. canariensis (Mill.)) Pit. and Proust (Figure 2.12)

Woody shrub 50-80 cm with glabrous stems. Leaves 4-7 cm, deeply dissected pinnatisect or more often bipinnatisect. Inflorescence spike up to 10 cm, branched at base of main spike. Bract lanceolate to ovate, acute, often with bluish tint, with five main nerves, slightly longer than calyx in flowering state. Upper middle lobe of calyx distinctly broadly triangular in shape. Corolla bicoloured, the lower lobes violet fading to blue-violet on the upper lobes with darker guidelines. Canary Islands (Tenerife, Gomera, Gran Canaria, La Palma, El Hierro). Occasionally cultivated as an ornamental.

Figure 2.12 L. canariensis - plant in full bloom, Tenerife near Chio. (See Color Plate VII.)

Shrub 30 (50) cm. Leaves 3-6 cm, deeply dissected pinnatisect, elliptic, each lobe distinctly obovate, pedicel to 1-1.5 cm. Whole plant with a characteristic grey felt of very short branching hairs. Inflorescence spike compact up to 8 cm, branched at the base of the main spike. Bract elliptic, apex acute, with five rather indistinct nerves, exceeding the calyx in length. Upper middle tooth of calyx broadly triangular in shape. Corolla blue mauve. Canary Islands (Lanzarote) and Madeira. Occasionally cultivated as an ornamental.

10. L. buchii Webb and Berthel. (L. pinnata var. buchii (Webb and Berthel.) Benth.)

Shrub 50-70 cm. Leaves 5-8 cm, deeply dissected pinnatisect, ovate, lobes linear to ± obovate, pedicel 0.5-1 cm. Whole plant with a characteristic grey felt. Inflorescence spike up to 10 cm, sometimes branched at the base of the main spike. Bract ovate with acute apex, typically with five rather indistinct nerves, about 0.5-0.75 X the length of calyx. Upper middle tooth of calyx broadly triangular in shape. Corolla tube mauve blue. Canary Islands (Tenerife). Occasionally cultivated as an ornamental.

L. buchii var. buchii - flower spikes typically short 4-6 cm, branched many times and clustered at the end of the flower stalk. Leaf pinnatisect the lobes usually obovate, the terminal lobe ± diamond shaped. Northern region of Tenerife, particularly the Anaga Peninsula. L. buchii var. gracile M.C. León - flower spike typically long and slender usually over 10 cm, branched only once or twice. Leaf pinnatisect the lobes linear, the terminal lobe linear. Southern region of Tenerife, Teno region.

L. buchii var. tolpidifolia (Svent.) M.C. León — leaves linear lanceolate in outline, with irregular shallow to deep lobes. Teno region of Tenerife.

11. L. minutolii Bolle (L. foliosa Christmann)

Woody shrub 50-80 cm with distinctive very regularly pinnatisect leaves, ovate lanceolate in outline with a greenish/white indumentum of highly branched hairs. Flower stalk usually branched just once. Bracts ± same length as the mature calyx, ovate and long acuminate in shape, the tips tinged dark violet blue. The upper middle tooth of the calyx deltoid in shape. Flowers bicoloured. Canary Islands (Gran Canaria and Tenerife where the population is treated as var. tenuipinna Svent.). Occasionally cultivated as an ornamental.

12. L. rotundifolia Benth.

Woody based perennial with fleshy stems and leaves, glabrous. Leaves very distinctive broadly ovate to triangular ovate with margins that are highly variable, usually irregularly dissected and lobed occasionally more dentate or crenate. Bracts 0.75 to ± same length as calyx. Calyx teeth-lanceolate in shape, the middle posterior tooth slightly broader. Corolla red purple in colour, the lobes ± equal in size. Native to the Cape Verde Islands where it grows on cliffs mostly in elevated semi-arid to humid regions. Occasionally cultivated as an ornamental.

13. L. tenuisecta Coss. ex. Ball

Woody based perennial with a characteristic indumentum of short hooked stiff simple hairs with scattered sessile and short stalked glandular hairs, variably interspersed with longer scattered simple hairs. Leaves ovate in outline, usually pinnatisect often with secondary lobing. Bracts distinctive in shape ovate-lanceolate with a long acuminate apex about 0.6 X length of the calyx. Late flowering June to August. Endemic to Morocco, occurring in the High and Middle Atlas at altitudes over 1800 m.

14. L. maroccana Murb.

Woody based perennial with 50-80 cm glabrescent stems and long rather leafless sprawling stems. Spike is short, stout and compact, 1.5-3 cm long. The bracts are diagnostic with large membranous wings giving them an orbicular-pentagonal shape and a short sharp abrupt apex, c. 0.5 X length of the calyx. The upper middle posterior calyx tooth broadly deltoid, the others lanceolate in shape. Corolla violet-blue. Endemic to the High Atlas in Morocco occurring from sea level to 1700 m.

15. L. mairei Humbert var. mairei

A subshrub forming a dome shaped bush 40-50 cm high, the whole plant grey-green in appearance consisting of a distinctive indumentum of long white stiff hairs, variable in density over many short stalked glandular hairs. Leaves ovate-lanceolate in outline, 2-4 pinnatisect. Bracts very large 1.0-1.2 X length of the calyx, rhomboid in shape, the apex acuminate. The upper middle posterior calyx tooth broadly deltoid and shorter than the lateral pair, the lower pair narrowly lanceolate. Corolla dark violet. Endemic to Morocco occurring in the lower regions of SE High Atlas and adjacent ranges on open rocky habitats and desert plains.

var. antiatlantica Maire (L. antiatlantica Maire, L. mairei var. intermedia)

It differs in its indumentum of short stalked glandular hairs making the plant viscid with only a few scattered simple or branched non-glandular hairs. Bracts longer than in var. mairei 1.2—1.5 X length of the calyx with a long acuminate apex almost becoming spinescent. Endemic to the Anti-Atlas on open rocky habitats and desert plains.

16. L. antineae Maire (Figure 2.13)

Woody based perennial with erect and branching annual stems, usually quite leafy. Indumentum of short hooked stiff white hairs and longer simple to once-branched white stiff hairs, variable in density over sparse short stalked glandular hairs. Leaves pinnatisect ovate to ovate-lanceolate in outline. Bracts 0.5—0.75 Xlength of calyx, ovate-lanceolate with small thin wings, apex long acuminate. The upper middle posterior calyx tooth-deltoid in shape, the upper lateral lobes triangular, the lower lobes narrowly lanceolate. Corolla tube dark violet-blue the lobes becoming bright blue. Endemic to the Central Saharan Massifs of the Hoggar Mountains (Algeria) and Ai'r Mountains (Niger) on rocky mountains habitats over 1500 m.

17. L. coronopifolia Poir. (L. stricta Delile)

A woody based perennial forming a large bush of annual stems to 80 cm green to grey-green in appearance. Indumentum variable from glabresecent to sparsely pubescent. Leaves pinnatisect. Flowering stems distinctively branched, the common name stagshorn lavender reflecting the many branched peduncle. The flower spike tending to biseriate. The calyx teeth all narrowly

Figure 2.13 L. antineae — cultivated at Cambridge University Botanic Garden. (See Color Plate VIII.)

lanceolate in shape, the tips often tinged pink. Corolla sky blue to lilac, the corolla tube narrow and distinctly curved. The most widespread species of lavender occurring from the Cape Verde Islands, across North Africa, West Tropical Africa, NE Tropical Africa, Western Asia (Israel, Jordan and Iran) and the Arabian Peninsula. Found in open rocky and stony habitats and desert plains from ± sea level to c. 2000 m.

18. L. pubescens Decne.

A woody based perennial with clumps of annual stems 30-60 cm, the whole plant very glandular and highly aromatic. Stems have a distinctive indumentum of long white stiff hairs over numerous short stalked glandular hairs. Leaves ovate in outline, 2-3 pinnatisect. Flower spikes compact and unbranched. Bracts ovate with a long acuminate apex 0.6 to 1 X length of calyx. Corolla tube distinctly curved about 0.5 X along its length, violet-blue. Syria, Jordan, Israel, Egypt, Saudi Arabia and Yemen Arab Republic.

19. L. citriodora A.G. Miller

A woody based perennial, strongly aromatic and with a distinctive smell of lemons and a grey-green appearance. Indumentum of simple and branched non-glandular hairs and scattered sessile and stalked glandular hairs. Leaves ovate to broadly triangular in outline, pinnatifid. Spike simple only occasionally branched. Bracts broadly ovate with acute apex 0.75-1.5 X length of calyx. The upper middle posterior calyx tooth broadly triangular the lateral pair narrowly triangular, the lower pair of lobes narrowly deltoid. Corolla bright blue to violet. Endemic to Saudi Arabia and the Yemen Arab Republic found in open rocky habitats between 1900 and 2700 m.

Taxa of uncertain status L. sublepidota Rech. f.

This species is clearly closely related to L. coronopifolia and was described as differing particularly in its indumentum and also characters of the spike, bracts, calyx and leaves. It is native to Iran where L. coronopifolia also occurs, but appears to be known from only a single collection. It has not been possible to date to determine whether this is truly a distinct species or a variant that should be included within L. coronopifolia.

L. brevidens (Humbert) Maire

This taxon was originally described as a subspecies of L. coronopifolia and subsequently recognised as a distinct species. The identity and status of this taxon has seemed to be unclear in the literature and it has probably been a convenient name under which to place some rather aberrant specimens. The identity and status of this taxon is subject to a forthcoming paper by the author.

Hybrids

L. x christiana Gattef. and Maire

A hybrid only known in cultivation between L. canariensis and L. pinnata which first appeared in the 1930s in garden of J. Gattefosse at Ai'n-Seba in Morocco, where he cultivated both parents.

This hybrid is frequently misidentified and sold as either parent, L. canariensis or L. pinnata. Lavandula Sidonie™ originating from Australia is of this parentage.

Forms an attractive large woody shrub to 50-80 cm and now becoming quite widely cultivated. The plants appear to express hybrid vigour in forming such large plants, totally atypical of L. pinnata which usually only reaches 30 cm, and exceeding the usual dimensions of L. canariensis. The leaves resemble L. canariensis in form bearing the typical bipinnate lobing and have the dense white felt of L pinnata. The large bracts exceeding the calyx in length are typical of L. pinnata. Flowers deep blue mauve.

L. x murbeckiana Emb. and Maire

A hybrid between L. maroccana and L. multifida first described by the Swedish botanist S. Murbeck (1859-1946) from among seedlings derived from L. maroccana growing in the Lund Botanic Garden, Sweden. The plants resemble L. maroccana the maternal parent most closely in their general appearance. The leaves are reminiscent of L. multifida, resembling their deeply bipin-natisect form closely. The stem indumentum bears sparse long stiff hairs typical of L. multifida although lacks the short branched hairs. In L. maroccana the stems are almost glabrous. The bracts and spikes are intermediate in character between the two parents. This hybrid appears only to be known from cultivation.

L. x canariensis Mill. X L. buchii Webb and Berthol. var. buchii

This hybrid appears to occur infrequently in the wild where the two parents overlap, in the northern part of Tenerife. Forms a woody shrub to c. 100 cm with bipinnatisect leaves (resembling L. canariensis) with narrow lobes and usually with a white indumentum (resembling L. buchii). The form and branching of the peduncle is very typical of L. canariensis, the spikes not being clustered at the apex of the peduncle as in L. buchii var. buchii. The spikes are slender, 5-10 cm long and not short and robust as in L. buchii var. buchii. The bracts in the two parent species are very similar, both being ovate acuminate in shape and 0.5-0.75 X the length of the calyx.

Section 5: Subnudae Chaytor

Typically woody based perennials or subshrubs with pinnatifid (lobed to only half the distance to midrib) leaves or sometimes leafless. The bracts are distinctly ovate in shape usually with a long spinescent apex and parallel veining except in L. somaliensis with reticulate veining. Bracts arranged spirally on the inflorescence axis subtending a single flower in each axil. Calyx 15-nerved, slightly two-lipped, the lobes subequal without an appendage. Nutlets bear a lateral scar 0.25-0.33 X length of the nutlet. The species are morphologically similar and mainly separated on characters of the indumentum, size and shape of the bract.

A section presently of eight species probably more native to the Arabian Peninsula (Saudi Arabia, Oman, the Republic of Yemen), Socotra and NE tropical Africa (Somalia) representing an important centre of diversification in the genus. A more detailed account of the species in this section has been published by Miller (1985). A few species are in cultivation within specialist collections and are all tender and some can be difficult to keep.

Key to species

1 Bracts ovate to obovate, ± abruptly tapering to a point with reticulate veining, leaves regularly pinnatifid (lobed to only half the distance to midrib) with simple segments L. somaliensis

Bracts ovate or narrowly triangular, forming a long spinescent tip, parallel veined;

leaves present with pinnatifid leaves with toothed segments or leaves absent 2

Indumentum of flower spike and lower stem with long soft simple hairs L. nimmoi

Indumentum of flower spike with fine short hairs, short woolly hairs or dense long woolly branched hairs 3

All stems 6—8 angled, bracts narrowed above to a fine bristle like tip L. setifera

All stems four-angled, bracts with stiff spinescent tip 4

Bracts 6.5—12 mm long, greatly exceeding calyx, calyx purple when in flower L. aristibracteata

Bracts 2—7 mm long, calyx green to grey-green or if purplish then bract not exceeding subtending bract in length 5

Plants ± leafless or with one or two leaves on lower part of stem 6

Plants leafy 7

Spike lax in fruit, plant branched from nodes and often tufted at upper nodes.

Sessile glands numerous in nerves between calyx L. macra

Spike condensed in fruit, plant branched mainly from the base. Few sessile glands between nerves on calyx L. subnuda

Bracts longer than calyx, calyx teeth ± reflexed in fruit; bracts and calyx with sparse indumentum of long woolly hairs L. galgalloensis

Bracts shorter than calyx rarely longer, calyx teeth erect in fruit; bracts and calyx with indumentum of fine short hairs or short woolly hairs 8

Stems and leaves densely hairy, upper leaves pinnatifid L. dhofarensis

Stem and leaves glabrescent or sparsely hairy, uppermost leaves typically entire with one or two teeth only L. subnuda

A sprawling almost leafless bush to 2 m, branching from the base. Stem indumentum variable glabrescent or with sparse simple and branched hairs. Lower leaves ovate in outline and pinnati-fid the upper ones becoming elliptic to rhombic and entire. Spike (1.5—)2—4(—8)cm long. Bracts ovate with a spinescent or narrowly triangular tip, 0.3-0.6 X as long as calyx (occasionally just exceeding calyx in length). Corolla variable in colour from shades of pale to dark blue. Endemic to Oman on rocky slopes, stony places and cliff crevices to 800 m.

21. L. macra Baker

A species very similar to L. subnuda but usually totally leafless or with very sparse leaves, tending to branch from nodes above the base, with several branches arising from a node giving a tufted appearance and the leaves which when present are always pinnatifid. Stem indumentum variable from glabrous or with simple or branched hairs. Spike 2-7 cm long elongating and becoming lax in fruit. Bracts ovate with a sharp to long spinescent tip, 0.25-0.33(^0.6) X length of calyx. Calyx with conspicuous sessile glandular hairs between nerves. Corolla pale blue to violet. Native to Oman, Republic of Yemen and Somalia among limestone hills and wadi beds to 1600 m.

22. L. dhofarensis A.G. Miller

Woody based perennial forming either dense or open straggly clumps with an indumentum of branched hairs throughout. Stems leafy to 40 cm. Leaves ovate to lanceolate in outline and

Figure 2.14 L. subnuda — cultivated at Cambridge University Botanic Garden. Section Subnudae. (See Color Plate IX.)

pinnatifid. Spike 1.5-6 cm. Bracts ovate with spinescent tip, (0.5—)0.75—1 X length of calyx. Corolla lilac, mauve or pale purple. Two subspecies are recognised: subsp. ayunensis — a plant forming a dense clump with erect stems, the upper internodes 2—4 cm and a dense white indumentum covering stem surface; subsp. dhofarensis — forming a more open straggling clump, the upper internodes (2—)4—9 cm and a sparse white indumentum not covering stem surface. Endemic to the Dhofar region of southern Oman. The subsp. dhofarensis occurs on escarpment mountains, subsp. ayunensis on the drier northern slopes of mountains.

23. L. setifera T. Anderson

A bushy often leafless perennial with slender wiry stems to 50 cm, 6—8 angled, glabrous or with an indumentum of simple or branched hairs. Leaves oblong-lanceolate in outline and pinnatifid. Spike 1.5—3 cm long. Bracts ovate or narrowly triangular narrowing gradually into a long bristle like tip, 1.25—1.5 X length of calyx. Corolla white or pale lilac. Native to the Republic of Yemen near Aden and Somalia, sea level to 30 m.

24. L. nimmoi Benth.

A perennial usually with a woody base. Stems slender, wiry and leafy on its lower parts 30—60 cm long with an indumentum of long simple hairs becoming glabrous above. Leaves ovate to oblong-ovate, pinnatifid to bi-pinnatisect. Spike 2—5 cm. Bracts ovate tapering to a sharp tip, 0.33-0.75 X length of calyx. Calyx with a distinctive indumentum of long simple hairs and sessile glands. Corolla clear blue. Endemic to Socotra.

25. L. galgalloensis A.G. Miller

Woody based aromatic perennial with twiggy stems leafy on the lower part, 15-60 cm. Leaves ovate in outline, pinnatifid. Spike 2-4cm. Bracts ovate with long spinescent tip, c. 1.25 X length of calyx. Calyx with an indumentum of long woolly hairs, the teeth reflexing in fruit. Corolla lilac. Endemic to northern Somalia growing on limestone escarpments, 1600-1800 m.

26. L. aristibracteata A.G. Miller (Figure 2.15)

Woody based aromatic perennial with leafy stems to 35 cm. Indumentum of simple and sessile glandular hairs. Leaves variable, elliptic, ovate, obovate to triangular in outline, simple or pinnatifid. Spike 2-5(-8)cm. Bracts often purplish tinged, ovate with a very long spinescent tip, 1.25-2 X length of calyx. Calyx distinctly purple-tinged, with fine short hairs, the teeth reflexed in fruit. Corolla blue or purplish blue. Endemic to the Surundi Hills in northern Somalia, 1500-2000m.

27. L. somaliensis Chaytor

Plant with numerous stems rising from a woody rootstock, leafy, simple or branched to 20-40 cm, with an indumentum of long woolly branched hairs. Leaves ovate to ovate-oblong in

Figure 2.15 L. aristibracteata - cultivated at Cambridge University Botanic Garden. Section Subnudae. (See Color Plate X.)

outline and regularly pinnatifid. Spike 1.5-3.5 cm. Bracts ovate to obovate, abruptly tapering to a sharp tip (acuminate), 0.3-0.75 X length of calyx, papery and with characteristic reticulate veining. Calyx with long woolly branched hairs and many sessile glandular hairs. Corolla blue. Endemic to the mountains of northern Somalia, 1600-1700 m.

Section 6: Chaetostachys (Benth.) Benth.

Herbaceous plants with green fleshy stems, distinctly rectangular with long internodes. Leaves numerous, usually large 7-10 cm and distinctly bipinnatisect. Flower stalks and spikes often branched. The single-flowered cymes are arranged spirally on the axis. Bracts ovate spinescent with parallel-veins. Calyx 15-nerved, the lobes ± subequal, slightly bilabiatae. Corolla twice the length of the calyx, lobes small, the lower middle lobe c. 2 X the size of the lateral lobes. Nutlets elliptic, black to dark brown in colour. Lateral scar present, over 0.75 X length of nutlet.

This section comprises the two native Indian species. It is characterised by their herbaceous nature, the large deeply bipinnatisect leaves and the nutlets which bear a lateral scar usually 0.75 X length of the nutlet. The corolla differs from other species in the lower median corolla lobe which is distinctly larger than the lateral lobes. The single-flowered cymes arranged spirally, the spinescent bracts and the subequal corolla lobes suggests its closest affinities are with section Subnudae. Not in general cultivation apart from a few specialist collections, tender and difficult to overwinter.

Key to species

Bracts concealing calyx L. gibsoni

Bracts only covering basal part of calyx L. bipinnata

28. L. gibsonii Grah.

Herbaceous plant up to 1 m with an indumentum of short soft hairs (pilose). Leaves with very short petiole, pinnate to bipinnate upto 13 cm long. Spike to 5.5 cm usually branched at base of spike. Bracts broadly lanceolate with acute apex, equal or slightly longer than calyx and concealing it. Corolla with rather small lobes. India, Deccan Peninsula.

29. L. bipinnata (Roth) Kuntze (Figure 2.16)

A highly variable herbaceous plant 15-100 cm. Indumentum of short hairs, particularly dense on stems and inflorescence. Leaves sessile or shortly petiolate, 2-12 cm long and usually distinctly bipinnatisect. Spike 4-7.5 cm, branching from base of spike. Bracts ovate tapering to a long sharp tip, 0.3 X length of calyx and only concealing the base of calyx. Corolla tube twice length of calyx, very pale blue in colour. Central and south India.

A number of varieties have been recognised based on shape and length of bract. Further study is desirable to determine if these are distinct taxa or represent natural variation in this species and hence have not been included in this treatment.

Other species

The following three species have not formally been classified within the present sectional classification and are subject to further work to clarify their position.

Figure 2.16 L. bipinnata — close up of flower, cultivated at Cambridge University Botanic Garden. Section Chaetostachys. (See Color Plate XI.)

30. L. hasikensis A.G. Miller

Woody shrub to c. 30 cm, with a characteristic dense white tomentose indumentum. Leaves oblong-ovate, small 0.2—1.5 cm long, with 1—3 pairs of rounded or ± triangular lobes. Spike capitate, c. 1 cm long, with single-flowered whorls, spirally arranged on axis, which lengthens in fruit to c. 4—5 cm. Bracts with a short sharp tip arising from between the two wing-like and membraneous ± orbicular lateral lobes, parallel-veined. Calyx 15-nerved, all five lobes ± equal in size and shape. Corolla tube c. 2 X length of the calyx, lilac in colour. Endemic to Dhofar.

An extremely distinct species of Lavandula with no clear affinities within the genus. The single-flowered cymes borne in a spiral arrangement, the subequal calyx teeth, form of the corolla and the biogeography of this species would suggest some affinity to section Subnudae. However, the capitate inflorescence with the rachis extending in fruit, the bracts which are parallel-veined and extremely broad with two wing like lateral orbicular lobes and the leaves which are oblong ovate with rounded or triangular lobes are all unique to this species and hence would be a rather anomalous in any of the presently described sections.

L. atriplicifolia Benth. and L. erythreae (Chiov.) Cufud.

The following two species which are native to the southern Arabian Peninsula and Ethiopia are evidently closely related. They are distinct and instantly recognisable by: their compact drooping spikes; the single-flowered cymes with bracteoles (none of the other single flowered species bear bracteoles) in a spiral arrangement on the inflorescence axis; the papery bracts ovate in shape with reticulate venation; the regular calyx with five lobes all equal in size and fifteen-nerved; the subequal stamens (unequal in all other Lavandula species) included within the corolla tube; and particularly the corolla which has five equal lobes (often described as star shaped) and are yellow brown in colour. The flowers are also described as having a musty odour, which together with their colour suggest they maybe fly pollinated.

These species have previously been classified within both Lavandula and a separate genus Sabaudia Buscal & Musch. They have been included within Lavandula in this treatment on the basis that these taxa bear the nectary lobes opposite the ovary lobes, the compact spike and stamen arrangement which are the main characters defining the genus Lavandula.

Key to species

Spike (1—)1.5—3 cm long, bracts 0.75—1 X length of calyx, interior of corolla tube glabrous, Saudi Arabia and Republic of Yemen L. atriplicifolia

Spike 1—1.5 cm long, bracts 0.5 X length of calyx, interior of corolla tube hairy, Eritrea L. erythreae

31. L. atriplicifolia Benth. (Sabaudia atriplicifolia (Benth.) Chiov.)

Woody perennial forming a bushy, weak stemmed aromatic shrub, 30—100 cm, the whole plant with a dense white indumentum. Leaves simple, entire and sessile, linear lanceolate in outline. Peduncle branched and bearing a compact drooping spike, 1.5-3 cm long. Bracts persistent, almost papery, obovate to circular in outline, 0.75-1 X length of calyx. Corolla c. 3 X the length of the calyx, the inside of the corolla tube glabrous, the five lobes all equal, narrowly lanceolate to triangular in outline, yellow brown in colour. Native to Saudi Arabia and the Republic of Yemen on dry rocky areas over 2500 m.

32. L. erythreae (Chiov.) Cufud. (Sabaudia erythreae Chiov.)

Woody perennial to 100 cm, the whole plant with a dense white indumentum. Leaves simple very rarely with 1-2 lobes, entire and sessile, lanceolate to narrowly elliptic in outline. Peduncle highly branched and bearing a compact drooping spike, 1—1.5 cm long. Bracts persistent, almost papery, obovate to circular in outline, 0.5 X length of calyx. Corolla c. 3 X the length of the calyx, the inside of the corolla tube hairy, the five lobes all equal, narrowly triangular to lanceolate in outline, the margins reflexed, pale yellow to yellow brown in colour. Native to Eritrea.

Intersectional hybrids

Several intersectional hybrids are recorded and are becoming widely grown as ornamentals particularly in Australia, New Zealand, South Africa and the Mediterranean.

L. x allardii Hy

Large woody shrub to 1.5—2 m tall (sometimes to 4 m), the stems with long internodes. Leaves sessile, linear to lanceolate, tending to obovate, with two distinct leaf types, either mostly entire or partially toothed with 1-7 teeth on each side above the centre and towards the apex. Both leaves and stems grey-green. Flower spikes long and narrow, 7—12 cm, often interrupted. Each cyme has 7—9(—11) flowers, bracteoles present. Bracts broadly ovate-lanceolate, tapering to a sharp apex and with no coloured bracts borne at apex of spike as in one parent L. dentata. Corolla shades of blue.

A sterile hybrid that originated in cultivation between L. dentata and L. latifolia. Flowers over a long period June—September in the United Kingdom. Not fully hardy only surviving a few degrees of frost. In frost-free areas it can make a good hedging plant and imposing specimen. A number of different clones appear to be in cultivation some of which have been named: 'African Pride' — common in South Africa with occasionally toothed foliage; Clone B — refers to material from Australia with mainly toothed foliage.

L. x heterophylla Poir.

A hybrid originating in cultivation between L. dentata and L. angustifolia. Similar in general appearance to L. x allardii, but it would appear to be a less vigorous plant and with much smaller bracteoles which are obvious as in L. x allardii. Many plants grown under this name are probably L. x allardii and this cross appears to be rare in cultivation. Further work is required to confirm the identity of L. x heterophylla.

A bushy woody shrub to 75 cm. Leaves lanceolate to obovate with a dense silver grey indumentum, the leaves entire or often toothed. Flower spikes conical in shape 6—10 cm with purple mauve flowers. Bracts diamond shape, violet coloured at least when young, more or less becoming sterile near apex of the spike and forming a small tuft of bracts (a coma) present, bracteoles 2—3 mm. Corolla deep violet-blue.

The cultivar 'Goodwin Creek Grey' selected and bred in the United States appears to be the only cultivar available with this parentage.

References

Andrew, S. (1994). Lavenders in Cultivation. The Lavender Bag, 1: 1—12.

Brummitt, R.K. and Powell, C.E. (1992). Authors of Plant Names. Royal Botanic Gardens, Kew. Cantino, P.D., Harley, R.M. and Wagstaff, S.J. (1992). Genera of Labiatae: Status and Classification. In R.M. Harley and T. Reynolds (eds), Advances in Labiate Science: 511—22. Royal Botanic Gardens, Kew.

Chaytor, D.A. (1937). A Taxonomic Study of the Genus Lavandula. Journal of the Linnean Society — Botany 51: 153—204.

Gingins De La Sarraz, F.C.J. (1826). Histoire Naturelle des Lavandes. Paris.

Green, M.L. (1932). Botanical Names of Lavender and Spike. Kew Bulletin: 295—7.

Lundmark, J.D. (1780). De Lavandula. Dissertatio Academica. Uppsala.

McNaughton, V. (2000). Lavender, the Grower's Guide. Garden Art Press. Woodbridge.

Miller, A.G. (1985). The Genus Lavandula in Arabia and Tropical NE Africa. Notes of the Royal Botanic

Garden, Edinburgh 42(3): 503—28. Rozeira, A. (1949). A Secciao Stoechas Gingins do genero Lavandula L. Brotéria Série de Ciîncias Naturais 18(46): 1—82.

Suarez-Cervera, M. and Seoane-Camba, J.A. (1986). Taxonomía numérica de algunas especies de Lavandula L., basada en caracteres morfologicos, cariologicos y palinologicos. Anales del Jardin Botanico de Madrid.

Suarez-Cervera, M. and Seoane-Camba, J.A. (1989). Estudio morfologico del genero Lavandula de la

Peninsula Iberica. Biocosme Mésogéen, Nice 6(1-2): 21-47. Tucker, A.O. and Hensen, K.J.W. (1985). The cultivars of Lavender and Lavandin (Labiatae). Baileya 22(4): 168-77.

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