Plant Family Characters | MALVACEAE | Southern Africa
Plant Family Characters | MALVACEAE | Southern Africa - Southern Africa : MALVACEAE OF SOUTHERN AFRICA Malvaceae (sensu lato) [Malvaceae - including Sterculiaceae, Tiliaceae and Bombacaceae] (Subclass: Dilleniidae - Order: Malvales) Diagnostic features: Malv
Malvaceae (sensu lato)
[Malvaceae - including Sterculiaceae, Tiliaceae and Bombacaceae]
(Subclass: Dilleniidae - Order: Malvales)
Diagnostic features: Malvaceae has no features exclusive to the family, therefore it is a set of features, which are:
- Leaf arrangement: alternate (pic 1) (present in many families)
- Stipules: present (pic 2) (present in many families)
- Stellate (star-shaped) hairs, usually (pic 3) (present in many families including Annonaceae, Asteraceae, Brassicaceae, Euphorbiaceae etc.)
- Flowers: bisexual (or unisexual), regular (pic 4) (present in many families)
- Calyx: 3-5-merous, often subtended by an epicalyx (pic 5) (epicalyx also present in Caryophyllaceae, Neuradaceae, Roridulaceae and Rosaceae)
- Corolla: 5-merous, petals free (not joined together in a tube) (pic 4) (present in many families)
- Male whorl (androecium): numerous stamens monadelphous (joined into a tube around the style and joined to it) (pic 6) (present in several families including Amaranthaceae, Fabaceae and Geranciaceae)
- Female whorl (gynoecium): ovary usually superior (above the attachment of the petals), composed of 1-many fused carpels (locules, chambers) with axile placentation. Style is branched (pic 6)
- Fruit: dry, capsular or schizocarpic (pods that break up into one-seeded sections) (pic 7) (except *Malvaviscus which has a berry)
- Seeds: often covered in fine hairs, usually contain little/no endosperm and have a straight or curved embryo (pic 8)
Habit herbs, shrubs or trees, usually with stellate hairs, sometimes prickly or with small scales. Leaves alternate, simple, entire to digitately lobed or partite, or palmate, usually palmately veined; stipules free, usually narrow or setaceous, often deciduous. Flowers regular, bisexual, sometimes unisexual on the same plant in the Sterculiodae, often showy, usually pedicelled, basically in thyrses with cymose partial inflorescences, but usually solitary or fascicled in leaf axils or racemose to paniculate; with or without epicalyx of 3-many free or connate segments. Calyx (3-)5-lobed or entire; lobes valvate. Petals 5, free but often adnate to base of staminal tube, convolute, rarely 0. Stamens many, hypogynous; filaments united into a staminal tube surrounding style (Malvoideae), outer whorl often reduced to staminodes or lacking (Sterculiodeae), tube ending in 5 small teeth to truncate (tribes Malvavisceae and Hibisceae) or split at apex into many filaments (tribe Malveae); anthers 1(2)-thecous, with longitudinal slits; pollen usually spinulose. Gynoecium superior, of 2-many, ± fused carpels with axile placentation, arranged around central persistent axis (torus or columella), with 1-many anatropous to campylotropous, bitegmic ovules, with zig-zag micropyles, in each locule/carpel; style simple, globose or club-shaped or more often branched, with branches as many or twice as many as carpels. Fruit a loculicidal (longitudinally dehiscing along the capsule wall between the partitions of the locule [the opposite is septicidal, dehiscing on the septum]) capsule or schizocarp, usually breaking into dehiscent or indehiscent carpels, rarely fleshy. Seeds reniform (kidney-shaped), subglobose or obovoid, glabrous or hairy; cotyledons folded; endosperm oily, proteinaceous, copious to 0.
Worldwide ± 90 genera, ± 2000 species; sthn Afr.: genera 22 (7 exotic), species ± 165. The family comprises many weeds. Sporadic escapes from cultivation include *Alcea rosea L. the Hollyhock, *Lagunaria patersonia G.Don, the Pyramid tree and *Malvaviscus arboreus Cav., the Wax mallow.
Key to Subfamilies and Genera of Malvaceae of southern Africa :
The links won't work if there are not yet observations of the taxon.
1a Gynoecium apocarpous (carpels free); petals, staminodes and epicalyx always lacking; androgynophore (extension of the receptacle between the petals and stamens on which the androecium and gynoecium are borne) present; flowers usually unisexual Sterculioideae S1
1b Gynoecium usually syncarpous (carpels fused); petals usually present; androgynophore, staminodes and epicalyx present or absent; flowers usually hemaphroditic (bisexual) 2
2a Stamens usually free Grewioideae G1
G1a Fruit a somewhat fleshy to dry, (1)2-4-lobed drupe Grewia G1b Fruit a glabrous, hairy or densely bristly capsule G2
G2a Flowers white, pinkish or mauve, 4-merous; some stamens sterile with no anthers or, if sterile stamens very few or apparently absent, the filaments nodose Sparrmannia G2b Flowers yellow, 5-merous, sometimes 4-merous but then capsule pod-like; all the stamens fertile, filaments never nodose G3
G3a Fruits globose, bristly, spiny or with conical, spine-tipped tubercles; ovules 2 per locule Triumfetta G3b Fruits usually long and pod-like, rarely ellipsoid or ovoid; ovules more than 2 per locule or, if only 2, then capsule smooth; leaves often tailed at the base Corchorus
2b Stamens usually forming a tube 3
3a Anthers usually monothecal (one pollen pouch), rarely paired; staminodes always absent; sepals usually fused more than 1/3 43b Anthers not monothecal; staminodes usually present; sepals usually fused less than 1/3 5
4a Trees, exceptionally shrubs; carpels 2-5; fruits capsules or indehiscent; endocarp often pubescent (abundant kapok or sparse pubescence); seeds usually glabrous; pollen usually without spines. Bombacoideae (Adansonia)4b Shrubs or herbs, exceptionally trees; carpels (3-)5-many; fruits schizocarps, less frequently capsules, rarely berries; endocarp glabrous; seeds sometimes pubescent; pollen spinose. Malvoideae (see key below)
5a Flowers usually in axillary cymes (oldest flowers at the apex) or solitary; epicalyx present; petals often persistent, flat, neither cucullate nor with apical appendage; cotyledons usually bifid; pollen usually sphaeroidal and spinose Dombeyoideae D1
D1 Fibrous herbs or undershrubs; petals becoming detached, persisting like a cap on the ovary; 5 fertile stamens Melhania D2 Shrubs or small trees; petals becoming papery, persistent; 10-15 fertile stamens Dombeya
5b Flowers variously arranged, often in sympodia; epicalyx usually absent (the corresponding bracts usually subtending flowers); petals usually caducous (falling early), sometimes cucullate (hooded or cowled) and/or with apical appendage; cotyledons only exceptionally bifid; pollen not spinose Byttnerioideae B1
B1a Ovary 5-locular B2 B1b Ovary 1-locular Waltheria
B2a Locules 2-ovulate; filaments ± connate into a tube; anthers oblong-elliptic, glabrous Melochia B2b Locules 3-many-ovulate; filaments free or slightly connate at the base, ± obovate or tuberculate-cruciform; anthers tapering to an acuminate apex, pubescent, pilose or ciliolate Hermannia
Key to genera of Malvoideae
1a Style branches twice as many as carpels (style branches usually 10, carpels 5) (tribe Malvavisceae) 21b Style branches as many as carpels (5-many) or style undivided and stigma more or less entire: 3
2a Epicalyx of (3-)5-16 filiform to broadly ovate, segments usually free (not joined at base); carpels without hooked spines Pavonia2b Epicalyx of 5 lobes fused in lower third; carpels with hooked spines *Urena
3a Fruit a capsule or indehiscent and woody to ± fleshy; staminal tube toothed at apex to truncate, bearing anthers on most or much of its surface (tribe Hibisceae) 43b Fruit a schizocarp with mericarps eventually separating from a persistent axis; staminal tube split at apex into many filaments (tribe Malveae) 12
4a Style simple (rarely very slightly divided at the tip), apex 5-lobed or clavate with ± coherent stigmas 54b Style divided apically into distinct branches; stigmas capitate to club-shaped 10
5a Calyx spathaceous, thin, splitting laterally and deciduous with the corolla *Abelmoschus5b Calyx not splitting laterally, truncate or regularly lobed, persistent 6
6a Calyx distinctly 5-lobed 76b Calyx truncate, entire or at most dentate or undulate 8
8a Epicalyx of 3 large, leaf-like, persistent bracts Gossypium8b Epicalyx of 3-8 small, narrow, deciduous bracts 9
10a Style 3(4)-branched; epicalyx of 3 large, leaf-like, persistent bracts Gossypioides10b Style 5-branched; epicalyx of 5-20 variable bracts, occasionally absent 11
12a Epicalyx absent 1312b Epicalyx present 16
13a Ovules 2 or more per locule; seeds mostly 2 or more per mericarp or sometimes 1 by abortion 1413b Ovules 1 per locule; seeds 1 per mericarp 15
15a Corolla cream to orange, rarely white; lateral walls or mericarps not disintegrating before fruit breaks up Sida15b Corolla blue; lateral walls of mericarps disintegrating before fruit breaks up *Anoda
16a Stigmas ± apical, usually with distinctly greater diameter than rest of style branches 1716b Stigmas decurrent on adaxial side of filiform to narrowly clavate style branches 22
17a Ovules 1 per locule 1817b Ovules or seeds 2 or more per locule 19
19a Mericarps ± divided into 2 compartments by a transverse partition 2019b Mericarps not divided into 2 compartments 21
21a Lateral walls of mericarps with a clearly demarcated reticulate-fenestrate area in lower third *Sphaeralcea21b Lateral walls of mericarps smooth or variously ridged to obscurely reticulate-fenestrate Anisodontea
22a Epicalyx of 6-10 bracts Althaea22b Epicalyx of 3 bracts 23
Please note that plant families are based on ovary and ovule characteristics which are generally not readily visible in the field, and often require a microscope. I have tried to make these descriptions as painless as possible with macro characteristics, but sometimes I have had to resort to the small and annoying.
AcknowledgementsDavid Gwynne-Evans has kindly allowed me to use some of his photos.
Robert (Cassine) generously helped with the subfamily key, proofreading and some references. Thank you Robert!
All the iSpotters who gave me help, encouragement and lekker suggestions - dankie okes!
Bayer, C. [et al. 1999], Fay, M. F., de Bruijn, A. Y., Savolainen, V., Morton, C. M., Kubitzki, K., & Chase, M. W. 1999. Support for an expanded family concept of Malvaceae within a recircumscribed order Malvales: A combined analysis of plastid atpB and rbcL DNA sequences. Bot. J. Linnean Soc. 129: 267-303.
Bayer, C., & Kubitzki, K. 2002. Malvaceae, pp. 225-311, in Kubitzki, K. (ed.), The Families and Genera of Vascular Plants. V. Flowering Plants. Dicotyledons. Malvales, Capparales and Non-betalain Caryophyllales. Springer, Berlin.
Heywood, V. 1993. Flowering plants of the world. Oxford University Press, New York.
Heywood, V, Brummitt, R.K., Culham, A. & Seberg, O. 2007. Flowering plant families of the world. Royal Botanic Gardens, Kew.
Leistner, O. A. 2000. Seed Plants of southern Africa: families and genera. Strelitzia 10.