KEW BULLETIN (2020) 75: 51
DOI 10.1007/S12225-020-09911-6
ISSN: 0075-5974 (print)
ISSN: 1874-933X (electronic)
Discovered online: Hibiscus hareyae sp. nov. of sect. Lilibiscus
(Malvaceae), threatened in coastal thicket at Lindi, Tanzania
Lex A. J. Thomson1 & Martin Cheek2
Summary. The spectacular new species with horticultural potential described in this paper, Hibiscus hareyae L.A.J.Th-
omson & Cheek, was identified during an assessment of online digitised botanical specimens of H. schizopetalus (Dyer)
Hook.f. as part of a review of species in Hibiscus sect. Lilibiscus Hochr. A short updated description and delimitation of
the horticulturally important sect. Lilibiscus is presented. Flowering and fruiting specimens of Hibiscus hareyae are readily
distinguished from H. schizopetalus by their short (0.4 – 2 (– 4.5) cm long, non-articulated peduncle-pedicels vs (6 –) 8 –
11 (– 14) cm long, articulated peduncle-pedicels, and larger, broader epicalyx bracts (1.5 – 4 × 1 – 1.2 mm vs 0.6 – 1.5 ×
0.1 – 0.3 (– 0.5) mm), the epicalyx forming a shallow cup 0.5 – 1 × 2 – 3 mm vs bracts appearing free. The absence of an
articulation of the peduncle-pedicel of H. hareyae is unique within sect. Lilibiscus. The species is also well-marked from
H. schizopetalus by other morphological differences in corolla and foliage, and in ecology and geography. Hibiscus hareyae
has a restricted natural distribution as an element in deciduous coastal thicket, usually on coral rag formations,
sometimes in or near mangrove, in Lindi Province, southern Tanzania. It ranges from the Indian Ocean coast to as
much as 20 km inland, from about 8.5oS to 10oS (c. 140 × 20 km) and is assessed as Vulnerable (VU B2ab(iii)). Hibiscus
hareyae has high ornamental potential but is unknown in cultivation.
Key Words. Africa, conservation, coral rag, Hibiscus schizopetalus, horticulture.
Introduction
In the early 1870’s, Dr John Kirk found a dry-season
deciduous Hibiscus with laciniate petals growing on a
dry rocky slope near Kilwa Kisiwani in south-east
Tanzania, then a significant port in E Africa. Later,
in September 1873 he found a similar Hibiscus, also
with laciniate petals growing 300 miles away in a
“damp, mountain glen in the Wanika Hills”, near
Mombasa in south-east Kenya. Kirk considered these
to be variants of the same species, with morphological
differences being attributed to the different environmental conditions in which the Hibiscus were growing,
and he presumed that geographical and morphological intermediates existed (Kirk & Oliver 1877). Public
attention was first drawn to the plants by Kirk & Oliver
(1877), and they were initially considered as a variety
of Hibiscus rosa-sinensis L., (Boulger 1879; Masters
1879; Thistleton-Dyer 1879) before the variety was
elevated to species rank as H. schizopetalus (Dyer)
Hook.f. (Hooker 1880). Seed of the Kenyan plants
came into cultivation in London in 1874 and it was
subsequently spread throughout the world as a
tropical ornamental plant. In 1874 Kirk sent unnumbered specimens of both the Wanika Hills and Kilwa
collections to Kew (Cheek 1989) where these were
mounted on a single herbarium sheet and later
assigned barcodes K000240991 and K000240492. In
January 1884 Kirk (1884) sent two more specimens to
Kew of the southern Tanzanian Hibiscus, collected
from Lindi in Nov. 1877 and in July 1877: these were
mounted on another herbarium sheet (assigned
K000240493 and K000593146). Subsequently, eight
additional botanical collections were made of the
southern Tanzanian Hibiscus, which was found to be
a new species. The new species, here described as
Hibiscus hareyae L.A.J.Thomson & Cheek, was identified during an online assessment of digital images of
botanical specimens of H. schizopetalus (Dyer) Hook.f.
as part of a review of sect. Lilibiscus by the first author
and confirmed by examination of herbarium material
The genus Hibiscus L., as currently delimited, with
1449 names listed by IPNI (continuously updated),
comprises 422 accepted species (POWO 2020). Species of the genus are pantropical and subtropical, but
with some representation in the temperate zone. They
vary from annual herbs to small trees. The flowers
usually have an epicalyx with >5 or usually many more,
free or partly united, usually narrowly triangular, nonfoliose, non-fleshy, bracteoles. The styles bear five
branches, each terminating in a capitate stigma. The
fruit is a 5-valved, dehiscent loculicidal capsule, each
locule holding three or more seeds. New taxa of
Accepted for publication 14 July 2020. Published online 9 December 2020
1
Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland, 4558, Australia.
2
Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, UK. e-mail: m.cheek@kew.org
© The Author(s), 2020
51 Page 2 of 10
Hibiscus are still steadily being discovered and published e.g. Hibiscus vitifolius subsp. lukei Mwachala
(Mwachala & Cheek 2003), H. bennettii L.A.J.Thomson
& Braglia (Thomson & Braglia 2019) and H. fabianae
Cheek (Cheek et al. 2020)
Sect. Lilibiscus Hochr.
Shrubs, sometimes scandent, or small trees, usually
with unlobed, ovate, glossy leaves. Flowers single,
axillary, usually with an articulated peduncle. Involucre (epicalyx) of 5 – 10, more or less linear or narrowly
triangular bracts, usually shorter than the calyx and
never fused with each other or with the calyx. Calyx
united into a tube, lobes shorter than tube. Involucre
and calyx glabrous or only slightly tomentose with
stellate and simple hairs. Corolla large and bright, the
petals reflexed at anthesis leaving the staminal column
conspicuously exserted. Fruit capsular, usually obovoid
and glabrous or scabrous, but never woolly. Seeds
smooth, verrucate, or hairy.
Section Lilibiscus, comprising 23 species (several of which
have previously been treated as subspecies), is restricted
mainly to islands in the Indian and Pacific Oceans. It is
monophyletic and sister to Sect. Hibiscus according to Pfeil
et al. (2002) although with poor sampling. According to
Thomson & Braglia (2019), nine species are known from
Hawaii, those with predominantly white flowers being
H. waimeae A.Heller, H. hannerae O.Deg. & I.Deg.,
H. arnottianus A.Gray, H. immaculatus Roe,
H. punaluuensis Skotsb. and those with orange or red
flowers being H. kokio Hillebr. ex Wawra, H. kahili
C.N.Forbes, H. saintjohnianus Roe, H. clayii O.Deg. &
I.Deg. Four species have been recorded from Fiji:
H. storckii Seem., H. bennettii, H. bragliae L.A.J.Thomson,
H. macverryi L.A.J.Thomson & Braglia (Thomson &
Braglia 2019). Hibiscus cooperi Hort. has recently been
confirmed growing in its native state in the interior of
Erromango, Vanuatu (Joe James Rungu, pers. comm.).
In the Indian Ocean, four species (Hibiscus boryanus
DC., H. fragilis DC., H. genevii Bojer ex Hook., H. liliflorus
Cav.) are known from the Mascarene Islands and from
Madagascar five species (H. bernieri Baill., H. grandidieri
Baill., H. phanerandus Baker, H. perrieri Hochr., H. liliastrum
Hochr.), while H. schizopetalus and H. hareyae, described in
this paper, are restricted to the Indian Ocean coast of E
Africa. Two taxa, H. rosa-sinensis and H. denisonii Hort. are
only known from horticulture. Plants of section Lilibiscus,
especially H. rosa-sinensis and its hybrids are the most
commonly cultivated ornamentals of the genus.
Taxonomic Treatment
The lectotype of Hibicus schizopetalus (Dyer) Hook.f. is
Kirk s.n. (K!, chosen by Cheek (1989)) from Kenya,
© The Author(s), 2020
KEW BULLETIN (2020) 75: 51
Mombasa District. This specimen (Kew barcode
K00240991, lectotype) was a mixed collection, with a
different element subsequently barcoded K000240492
on the same sheet. Furthermore, the area on the sheet
coded K000240492 includes specimens which are a
mixture of H. schizopetalus and H. hareyae sp. nov. The
only material of H. hareyae on this sheet is the short
leafless stalk with a single flower on a short peduncle
at the top right of the specimen sheet. The handwritten location ‘Kilwa’ in the hand of Daniel Oliver,
Keeper of the Kew Herbarium, appears misplaced on
the sheet and ought to have been pointing to the
floral fragment of H. hareyae in the top right corner,
rather than to the undoubted specimen of
H. schizopetalus.
Hibiscus hareyae although superficially similar to
H. schizopetalus, is a distinctive and well-marked
species. Whilst H. hareyae is closely related to, and
shares many features including two distinctive floral
traits with, H. schizopetalus — laciniate petals and
pendant flowers — it differs in other taxonomically
significant floral and foliar morphological characters
(Table 1). These differences with H. schizopetalus
indicate that it warrants species-level recognition.
The absence of an articulated floral stalk is unique in
sect. Lilibiscus. The two species have an allopatric
distribution with the nearest populations separated by
a distance of about 400 km. Examination of specimens
of H. hareyae from northern Tanzania indicated no
evidence of morphological intermediates or gene
exchange between populations of the two species.
The name Hibiscus schizopetalus is globally associated
with plants of the Kenyan and northern Tanzanian
species: this species is now widely planted throughout
the tropics and subtropics, and also as a glasshouse/
indoor plant in cooler climates. Planted in gardens as
an ornamental it can often persist and become locally
naturalised. Naturalised populations deduced from
this source were observed in Cameroon in 2007 and
Guinea in 2012 (Cheek pers. obs). On the Tropicos
website of herbarium specimens of wild plants, of the
38 listed of Hibiscus schizopetalus, 28 are from Central
and South America where the species is definitely not
native, as is the case also for the records from Gabon
and Mozambique (Tropicos.org 2020). We consider
that most of the few specimens of H. schizopetalus from
central-eastern Tanzania are likely to be naturalised or
old plantings of H. schizopetalus, on this basis. For
example the label of one specimen of H. schizopetalus
from central Tanzania (H. Breyne 5562,
BR0000019387017) collected along the Dar es Salam
– Morogoro road states that it was introduced and
naturalised in gallery forest.
Cheek’s (1989) rationale for choice of lectotype is
sound and fortuitously minimises any disruption with
continuing the existing use of the name Hibiscus
schizopetalus.
KEW BULLETIN (2020) 75: 51
Materials and Methods
The new species was first discovered by the first author
by examining online images of herbarium specimens
including the Kew Herbarium catalogue (continuously
updated), and examining them for morphological
disjunctions. Gross morphological measurements were
initially made from these images. Finally, herbarium
material at K was examined with a Leica Wild M8
dissecting binocular microscope fitted with an eyepiece graticule measuring in units of 0.025 mm at
maximum magnification. The drawing was made with
the same equipment with a Leica 308700 camera
lucida attachment. Specimens or their high resolution
images were inspected from the following herbaria:
BM, DSM, EA, FTG, K, MO and P. Names of species
and authors follow IPNI (continuously updated). The
format of the description follows those in other papers
describing new taxa of Hibiscus Sect. Lilibiscus e.g.
Thomson & Braglia (2019), Cafferty & Cheek (1996),
Cheek et al. (1998). Technical terms follow Beentje &
Cheek (2003). Specimens cited which have been seen
are indicated “!”. The conservation assessment follows
the IUCN (2012) categories and criteria. Herbarium
codes follow Index Herbariorum (Thiers, continuously
updated). The map was made using simplemappr
software (https://www.simplemappr.net/).
New Species
Hibiscus hareyae L.A.J.Thomson & Cheek sp. nov. Type:
Tanzania, Lindi Province, “Collected July 1877. Lindi,
E. Africa, Lat. 9 40’ South this extends its habitats a
little further South than before”, Kirk s.n. (holotype
K00240493!) (Fig. 1).
http://www.ipni.org/urn:lsid:ipni.org:names:77213108-1
Syn. Hibiscus schizopetalus auct., non (Dyer) Hook.f.
sensu Mwachala (2009: 60) pro parte
Deciduous erect, sprawling, to scandent shrub, 2 – 4 m tall, to 6
m wide, often leafless or near-leafless at onset of
flowering. Branches slender, pendulous arching to the
ground; bark grey with white blotches. Branchlets light
grey-green, becoming waxy-white, smooth or finely
ridged, 2 – 3 mm diam., internodes 1.2 – 1.8 (– 4.5) cm
long, glabrous. Leaves deciduous during the dry season;
light green above, ovate, oblong or elliptic, 1.8 – 3.0 (–
4.7) × 0.9 – 1.5 – 1.8 (– 3.5) cm, apex obtuse-rounded,
base obtuse, finally abruptly rounded, nerves palmate at
base, midrib with 2 – 3 secondary nerves on each side of
the midrib, nerves prominent below; teeth (1 –) 3 – 5 (–
10) per side, large rounded-crenate , 1 (– 2) × c. 2 – 3 (–
5) mm, margin slightly thickened, lined with appressed,
simple, stout, colourless unicellular hairs c. 0.3 mm long,
abaxial surface of leaf with pale golden stellate hairs
Page 3 of 10 51
thinly scattered, 0.3 (– 0.5) mm diam., arms appressed,
stout. Stipules brown-purple, glossy, broadly triangular,
0.5 – 1.25 × 0.5 – 1 mm, sparsely hairy, persistent for
several nodes from stem apex. Petiole 3 – 6 (– 50) mm
long, slightly canaliculate, densely pubescent with long,
white, sinuous simple hairs 0.3 mm long, tapering to a
long acute apex. Flowers often on leafless branches, 6 –
8.5 cm wide, solitary or more typically clustered in upper
leafless axils on pendant peduncle-pedicels. Pedunclepedicels stout 0.4 – 2 (– 4.5) cm long, longitudinally
ridged, sparsely puberulent with a mixture of stellate and
simple hairs, stellate hairs 3 – 7-armed, 1 – 2.5 mm wide,
simple hairs patent, 0.5 – 1 mm long, when immature
densely papillate with multicellular papillae 0.05 mm
long. Epicalyx bracts 7 – 8, united at base forming a
shallow cup 0.5 – 1 × 2 – 3 mm, bracts pale green, 1.5 – 4
× 1 – 1.2 mm, narrow-lanceolate, outer surface sparsely
covered (c. 10% of surface) mainly in stellate hairs 3 – 4armed, 1 – 2 mm long, simple hairs 0.5 – 1.5 mm long.
Calyx pale green, slightly campanulate, tube c. 2 cm long
× 4 mm wide at base to 1 cm wide at apex, 3 – 4-lobed,
lobes triangular 4 – 5 mm long, outer surface sparsely
covered (10 – 20% of surface) in mainly simple, patent
hairs 0.5 – 1 mm long, with a few stellate hairs (as
epicalyx). Petals 5, shortly clawed, claw c. 0.3 × 0.2 cm,
laterally compressed, blade ovate-elliptic, c. 3 – 3.5 × 2.5 –
3 cm, pinnatifid, divided 1=2 – 2=3 to the midline, c. 8
segments each side, with the distal segments 1 – 2 mm
wide and bifid or trifid, basal segment pair, oblong, 1 –
1.3 × 0.5 cm, segments slightly recurved, adaxial surface
deep rose-pink or burgundy red, with an extensive (50 –
75%) white/pale pink basal zone, abaxial surface rosecrimson, also described as red (Kayombo 4590, MO) or
red and yellow (Semsei S633, K). Staminal column (4 –) 5
– 6 cm long, rose pink, slender, antheriferous in terminal
25 – 30%. Stamens 100 – 110, filaments 7 – 10 mm long,
pink, anthers orange, oblong 7 – 9 × 5 – 6 mm, pollen
yellow or orange. Style exserted c. 1 cm beyond
androecium, then dividing into 5, slender, spreading
branches, c. 14 – 20 mm long, crimson. Stigma pads
minute-capitate, c. 1 mm diameter, crimson. Fruit 5valved capsule, c. 2.2 cm long × 0.8 cm wide, pale-green,
valves acuminate. Seeds unknown. Figs 1 – 3.
RECOGNITION . Within Hibiscus, H. hareyae and
H. schizopetalus are the only two species with laciniate
petals. Hibiscus hareyae is readily distinguished from
H. schizopetalus by its much shorter and non-articulated
peduncle-pedicels (0.4 – 2 cm long vs 8 – 14 cm long
and articulated); longer and broader epicalyx bracts,
(1.5 – 4 × 1 – 1.2 mm vs 0.6 – 1.5 × 0.1 – 0.3 (0.5) mm,
the epicalyx forming a shallow cup 0.5 – 1 × 2 – 3 mm,
vs bracts appearing free (for additional diagnostic
characters see Table 1).
DISTRIBUTION. Tanzania (Map 1). The species is
endemic to the Kilwa and Lindi Districts (Lindi
Region) of southern Tanzania. It is possible that the
© The Author(s), 2020
51 Page 4 of 10
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Table 1. Diagnostic differences between Hibiscus hareyae and H. schizopetalus.
Peduncle-pedicel
Epicalyx bracts
Corolla
Number of anthers
Typical leaves
Habit
Stipules
Natural distribution
Ecology
Hibiscus hareyae
Hibiscus schizopetalus
0.4 – 2 (– 4.5) cm long; non-articulated
Narrowly triangular, 1.5 – 4 × 1 – 1.2 mm long,
persistent, united at base into a shallow cup 0.5 – 1 ×
2 – 3 mm
Petals slightly reflexed, 3 – 3.5 × 1 – 1.5 cm (near base)
100 – 110
Deciduous. Ovate, elliptic or oblong, 1.8 – 3.0 × 0.9 –
1.5 cm wide; margin large rounded-crenate leaf
teeth, 2 – 3 mm across, 3 – 5 teeth per margin
Erect to scandent shrub, 2 – 4 m tall
Brown-purple, glossy, broadly triangular, sparsely
hairy, 0.5 – 1.25 × 0.5 – 1 mm, persistent for
several nodes from stem apex
Lindi and Kilwa Provinces, S Tanzania
Deciduous coastal thicket usually on coral rag,
sometimes at edge of mangrove
(6 –) 8 – 11 (– 14) cm long, articulated
Linear to narrowly oblong, 0.6 – 1.5 × 0.1 – 0.3 (– 0.5)
mm long; caducous, sometimes abortive, appearing
free, the base not forming a cup
Petals reflexed in an arc, 3.5 – 5.5 × 0.5 (near base)
60 – 80
Evergreen. Lanceolate to ovate-elliptic, 3.5 – 7.5 × 1.2 –
4 cm wide; margin serrate-dentate (entire toward
rounded base), 6 – 10 teeth per margin
Shrub scandent, or small forest tree, 2.5 – 5 (– 8) m tall
White, subulate, densely covered in hairs, 0.5 – 1 × 0.1
mm, rapidly caducous
species might yet be found in northern Mozambique
but it was not recorded as wild there by Exell (1961).
SPECIMENS EXAMINED. TANZANIA. Lindi Province: Kilwa
Distr., T8 – N end of Mbarawala Plateau, 7 Nov. 2003,
C. J. Kayombo 4590 (MO 5750577 image!); Kilwa Distr.,
Kilwa South – pt451, 0908S, 3920 E, fl. 25 Nov. 2003,
W. R. Q. Luke & O. Kibure 9718 (MO5792757 image!,
FTG122084 image!) (EA, K000593145!, LMA, NHT);
Kilwa Distr., 32 km N of Lindi, Mchinga S, pt 552, fl.
20 Dec. 2003, W. R. Q. Luke & O. Kibure 10203
(FTG122085 image!); Lindi Distr., c. 6.5 km N of
Lindi, fl. 9 Dec. 1955, E. Milne-Redhead & P. G. Taylor
7481, 9 Dec. 1955 (BR image!, K000593143!,
K000593144!); Lindi, “Lat. 9 40’ South, this extends
its habitats a little further South than before”, fl.
July 1877, Kirk s.n. (holotype K000240943!); Lindi, fl.
Nov. 1877, Kirk s.n. (K000593146!); Lindi, 40 km
westlich, 200 – 250 um. Mangrovenrade, fl. 26
Aug. 1934 (Schlieben 5184 (BM!, P06593493 image!);
Lindi Region, Lindi Distr., Lindi Creek, 10 00’S, 39
44’E, fl. 15 July 1995, G. P. Clarke 89 (K000593147!);
Lindi Distr., Lindi Township, fl. Jan. 1952, Semsei S633
(K000593148!); Lindi, at Mdenga, coastal hills, fl.
buds, 26 Feb. 1936, Litchfield 5457 (K000593149!,
K000593150!); Lindi Region, Mtama Distr., Sudi
Village 10.16019E 39.96873S, fl. 12 Jan. 2020, O.
Suleiman, Darbyshire & Shah, Mbailwa 5526 (DSM, K,
NHT).
HABITAT. Hibiscus hareyae is found in coastal habitats
(“in the mangrove formation” Semsei S633), in the
ecotone between mangrove and thicket on coral rag
(Suleiman et al. 5526) and in “coastal thicket” (Luke &
Kibure 9718) or “coastal deciduous bushland” (MilneRedhead & Taylor 7481) on the edge of seasonally-dry
watercourses in thicket, and on hillsides (sea-level to
250 m alt.). There is a single record in “dry forest”.
Associated species (Suleiman et al. 5526) are Fimbristylis
© The Author(s), 2020
SE Kenya and NE Tanzania
Relictual semi-evergreen coastal forests
sp.; Euphorbia tirucalli Thunb., Dalbergia melanoxylon
Guill. & Perr., and Erythroxylum emarginatum Thonn.
Temperatures in the Lindi Region are rather
constant throughout the year, with the mean daily
temperature ranging from 25 – 28oC, and mean daily
maximum temperature of 31 – 32oC, and mean daily
minimum temperature of 20 – 24oC. The average
annual rainfall is around 900 mm falling between Dec.
and April, with a pronounced dry season of 6 – 7
months. Tropical cyclones, sometimes severe and
reaching category 4, occur infrequently from late
Dec. through to mid-April.
Hibiscus hareyae mainly occurs (Kilwa, Lindi and
Kiswa areas) on coral rag, a rubble-like limestone
formed by uplift of former marine coral reefs.
CONSERVATION STATUS. Hibiscus hareyae is known from
12 specimens and six threat-based locations. We
calculate the area of occupancy as 40 km2 using the 4
km2 cells favoured by IUCN (2012). The main location
is the town of Lindi, from which (or very nearby) seven
collections, from at least five sites have been made.
Two of these records refer to the species as occurring
in mangrove where it is “very common” (Schlieben 5184
and Semsei S633). Other than these collections, there
are few data on frequency, but recent research has
reported it as infrequent: during the survey of thicket
on coral rag resulting in collection of Suleiman 5526,
H. hareyae was only seen at a single site with just 4 or 5
individuals. Although this species was targeted by the
survey and other areas of coral rag were studied, no
further plants were found despite it being then
spectacular in flower (Darbyshire, RBG, Kew, pers.
comm. to Cheek Jan. 2020). Threats from agriculture
to thicket on coral rag substrate are low because coral
rag is uncultivatable. However large areas within the
range of the species along the coast have been
converted to salt pans which appears to have destroyed
KEW BULLETIN (2020) 75: 51
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Fig. 1. Hibiscus hareyae. Image of the holotype (K00240493), Kirk s.n. Tanzania, Lindi, July 1877.
© The Author(s), 2020
51 Page 6 of 10
KEW BULLETIN (2020) 75: 51
Fig. 2. Hibiscus hareyae. A habit, leafy shoot; B full-sized leaf, abaxial surface; C flowering shoot; D petal; E anther; F anther, inner
face; G anther, dorsal face showing filament insertion; H pedicel, epicalyx and calyx; J pedicel detail-indumentum; K calyx margin –
indumentum; L epicalyx lobe — indumentum. From Milne-Redhead & Taylor 7481. DRAWN BY ANDREW BROWN.
habitat. Several historic sites at Lindi may have been
lost due to house and road construction resulting from
© The Author(s), 2020
expansion of the town. At the site of Suleiman et al.
5526, much of the habitat had been cleared by cutting.
KEW BULLETIN (2020) 75: 51
Page 7 of 10 51
Fig. 3. Hibiscus hareyae. A leaves and inflorescence from above showing epicalyces; B flower from below showing white inner
petal markings. From Suleiman et al. 5526 (K). PHOTOS: A IAIN DARBYSHIRE, B TORAL SHAH.
Despite this, large areas of coral rag remain with
deciduous thicket more or less intact and so H. hareyae
although threatened to some degree, does not seem at
present at risk of imminent extinction across its range.
We advise that some of this overlooked habitat and its
threatened species be protected, perhaps as part of a
national Important Plant Areas programme
(Darbyshire et al. 2017). H. hareyae also ought to be
conserved ex situ including through seedbanking and
bringing into cultivation as an insurance policy against
the species becoming extinct in the wild as is believed
to be the case for other Tanzanian species such as
Kihansia lovettii Cheek (Cheek 2004), which has never
been seen since it was first collected, despite dedicated
searches over several years.
PHENOLOGY. Hibiscus hareyae has been recorded as
flowering from Nov. through to Feb. and July and
August. Immature fruits have been observed in Nov.,
with the main fruiting period likely to extend from
Dec. to March.
ETYMOLOGY. The specific epithet honours Dr Hareya
Fassil (12 Jan. 1968 – present) in recognition of her work
on conservation of plant genetic resources and the roles
of traditional plant-based medicines in Africa.
VERNACULAR NAMES. Mgongonyoka (Swahili) and
Kinyoka (Yau) (both Litchfield 5457); Lindi hibiscus
(English).
NOTES. The holotype of Hibiscus hareyae is barcoded
K000240493. It consists of two short stems both with
flowers. It is mounted in the top righthand corner of a
sheet at Kew with the pencilled label in the hand of
Kirk, separated at the very base of the sheet, also on
the right-hand side. Above this label is a separate
collection, a paratype, barcoded K000593146, of a
single flower in a packet annotated in the hand of J.
Hooker “Lindi, E.Africa, Dr Kirk, Nov. 1877” to which
the barcode K000593146 has been assigned. To the
left of the label is a larger packet containing the
folded manuscript note by Kirk that was published as
Kirk & Oliver (1877). It is annotated in the hand of
Oliver “Memorandum by Dr Kirk (18 Nov/74) to
accompany specimens of Hibiscus from Mombasa”
and “To be returned to Prof. Oliver”.
Below the holotype is a label in the hand of Oliver
stating “Sir J. Kirk distinguishes 2 vars (letter 10
Jan. 84). 1 from Kilwa (South! Shrub erect, often
leafless at flowering- unjointed in pedicel- this is the
var. sent herewith. Recd. At Kew/84.”
© The Author(s), 2020
51 Page 8 of 10
KEW BULLETIN (2020) 75: 51
Map 1. Hibiscus hareyae. Global distribution map.
Hibiscus hareyae is similar to H. schizopetalus, and we
postulate that both species are likely ancestral within
sect. Lilibiscus. It is likely that H. hareyae shares a
recent common ancestor with H. schizopetalus since
they are in geographic proximity, and are so
morphologically similar that they have been considered to be conspecific for 150 years. We hypothesise
that a single population formerly extended along the
coast from Kenya to southern Tanzania, adapting to
the different local environments at northern and
southern extremes, becoming separated from each
other due to extinction of the intervening populations. The northern evergreen plants, i.e.
H. schizopetalus are confined to the shady, damp
understorey of coastal semi-evergreen forest of hills,
especially Kaya forests, while the southern (H. hareyae)
is restricted to the drier habitats of deciduous coastal
thickets, and appear to be more xerophilous, with
smaller leaves and are at least partly and briefly
themselves deciduous. Similar species-pair disjunctions
between SE Kenya and S-Central Tanzania are seen
in the genus Ancistrocladus (Cheek et al. 2000). New
species to science continue to be discovered steadily
in Tanzania (e.g. Cheek & Bridson 2019), including
new taxa of Hibiscus e.g. H. kabuyeana Mwachala
(Mwachala 2009) and H. vitifolius subsp. lukei
(Mwachala & Cheek 2003).
© The Author(s), 2020
Deciduous thicket on coral rag and the Lindi
centre of endemism
Clarke (2001) documented the Lindi local centre of
endemism, within which falls the entire global distribution of Hibiscus hareyae. Forty to 91 vascular plant
species are recorded as being unique to this area,
focussed on the dissected plateaux inland of Lindi.
These plateaux are, southwards from the Rufiji River,
the Matumbi and Kichi Hills, the Ruwawa and
Mbwalawala plateaux, a series of plateaux inland of
Lindi, and the Makonde plateau (Clarke 2001). This
row of four large upland massifs rising to an elevation
of 945 m dominate the coastal hinterland of Tanzania.
Although Clarke included the coastal lowlands in his
centre, his focus is on forest, and coastal thicket is not
mentioned as a habitat for endemics or as a conservation priority. Coastal thickets on coral rag in
southern Tanzania appear to be understudied. Although H. hareyae is spectacular in flower over many
months, it was not recollected in the 56 years between
1877 (Kirk s.n.) and 1934 (Schlieben). Another species
restricted to this habitat in the Lindi area is Barleria
laceratiflora Lindau, known from only two collections
(Darbyshire et al. 2010: 406). Limestone habitats in
Africa such as coral rag can often host narrowly
endemic species of conservation importance (Cheek
et al. 2019).
KEW BULLETIN (2020) 75: 51
Dr John Kirk
The collector of the type and first three specimens
of Hibiscus hareyae, Dr John Kirk, was a British
surgeon, who was a life-long friend of Joseph
Hooker, Director of the Royal Botanic Gardens,
Kew. He became a keen and observant naturalist,
and following five years in central Africa as David
Livingstone’s chief officer on the second Zambezi
expedition, he accepted the post of surgeon and
Vice-Consul, Zanzibar (1866 – 1886), during which
time he visited Kilwa (1868) and Mombassa,
collecting the specimens of H. schizopetalus and
H. hareyae referred to in this paper. He rarely
published his own discoveries of botanical novelties,
preferring to “hand them over to Kew” (Polhill &
Polhill 2015: 242 – 244; Goyder 2014).
Page 9 of 10 51
of Dar es Salaam Herbarium, Tanzania; Missouri
Botanical Garden and Fairchild Tropical Botanical
Garden Herbarium, USA), Mr Quentin Luke (East
African Herbarium, National Museums of Kenya,
Kenya), Mr John Ndege (Migombani Botanic Garden, Tanzania), Ms Kirsty Shaw and Dr Paul Smith
(Botanic Gardens Conservation International).
The Keidanren Nature Conservation Fund through
a grant to Botanic Gardens Conservation International
has been supporting the ‘Developing conservation
horticulture and conserving threatened Hibiscus species in the Asia-Pacific Islands region’ and the first
author’s research on Hibiscus.
Early horticultural references
In his letter (30 Jan. 1884) to Sir William ThiseltonDyer (Kew Gardens), Kirk indicated that he was
planning on propagating cuttings of the ‘southern
variety’ to send to Kew, but an examination of
Kew’s records indicates that these were never
received. Hibiscus hareyae has high ornamental
potential (Fig. 3), and Kirk considered the Kilwa
(southern Tanzania) shrub better suited to cultivation than the larger, scrambling H. schizopetalus
from Mombasa (Kenya). Ironically, H. schizopetalus
has become a widely planted ornamental for the
tropics/sub-tropics whereas H. hareyae appears unknown in cultivation.
Open Access This article is licensed under a Creative
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licenses/by/4.0/.
Acknowledgements
The authors thank David Mabberley for suggesting
the collaboration that led to this paper and Roy
Gereau (Director of Tanzania Botanical Research
and Conservation Programme, Africa and Madagascar, Missouri Botanical Garden) for his valuable
assistance. Iain Darbyshire of the Royal Botanic
Gardens, Kew, asked to look out for this species on
a visit to coastal southern Tanzania with his
doctoral student Toral Shah and their Tanzanian
colleagues Haji. O. Suleiman and Y. S. Mbailwa, in
early 2020, is profoundly thanked for his success in
this endeavour, and for the resulting detailed
ecological and populational data and photographs
that feature in this paper. We also thank Kaj
Vollesen, RBG, Kew for discussion of the ecology
of the Lindi area. Xander van der Burgt kindly
produced the distribution map. We acknowledge
the generous help of the following organisations
and individuals in providing information, assistance,
images and access to botanical specimens: the
Natural History Museum London, UK; University
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