Plant family characters | Malvaceae

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:

1. Leaf arrangement: alternate (pic 1) (present in many families)
2. Stipules: present (pic 2) (present in many families)
3. Stellate (star-shaped) hairs, usually (pic 3) (present in many families including Annonaceae, Asteraceae, Brassicaceae, Euphorbiaceae etc.)
4. Flowers: bisexual (or unisexual), regular (pic 4) (present in many families)
5. Calyx: 3-5-merous, often subtended by an epicalyx (pic 5) (epicalyx also present in Caryophyllaceae, Neuradaceae, Roridulaceae and Rosaceae)
6. Corolla: 5-merous, petals free (not joined together in a tube) (pic 4) (present in many families)
7. 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)
8. 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)
9. Fruit: dry, capsular or schizocarpic (pods that break up into one-seeded sections) (pic 7) (except *Malvaviscus which has a berry)
10. Seeds: often covered in fine hairs, usually contain little/no endosperm and have a straight or curved embryo (pic 8)

Full description:
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

    S1 Stamens many, with anthers capitate on apex of staminal column Sterculia
    S2 Stamens 10(12), with anthers in a regular or wavy whorl around apex of staminal column Cola

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 4
3b 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) 2
1b 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 Pavonia
2b 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) 4
3b 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 5
4b Style divided apically into distinct branches; stigmas capitate to club-shaped 10

5a Calyx spathaceous, thin, splitting laterally and deciduous with the corolla *Abelmoschus
5b Calyx not splitting laterally, truncate or regularly lobed, persistent 6

6a Calyx distinctly 5-lobed 7
6b Calyx truncate, entire or at most dentate or undulate 8

7a Calyx with rows of black oil glands along veins Cienfugosia
7b Calyx without black oil glands Radyera

8a Epicalyx of 3 large, leaf-like, persistent bracts Gossypium
8b Epicalyx of 3-8 small, narrow, deciduous bracts 9

9a Fruit indehiscent, woody or somewhat fleshy Thespesia
9b Fruit a loculicidally dehiscent capsule Thespesia (was Azanza [included here but probably separable (Cassine)])

10a Style 3(4)-branched; epicalyx of 3 large, leaf-like, persistent bracts Gossypioides
10b Style 5-branched; epicalyx of 5-20 variable bracts, occasionally absent 11

11a Ovules and seeds solitary in each locule Kosteletzkya
11b Ovules and (mostly) seeds 2 or more in each locule Hibiscus

12a Epicalyx absent 13
12b Epicalyx present 16

13a Ovules 2 or more per locule; seeds mostly 2 or more per mericarp or sometimes 1 by abortion 14
13b Ovules 1 per locule; seeds 1 per mericarp 15

14a Mericarps 5-40, not divided Abutilon
14b Mericarps 3-5, ± divided into 2 compartments by a transverse constriction Wissadula

15a Corolla cream to orange, rarely white; lateral walls or mericarps not disintegrating before fruit breaks up Sida
15b 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 17
16b Stigmas decurrent on adaxial side of filiform to narrowly clavate style branches 22

17a Ovules 1 per locule 18
17b Ovules or seeds 2 or more per locule 19

18a Petals yellow; mericarps with 1 apical and 2 dorsal awns pointing outward *Malvastrum
18b Petals pink, mauve, purple or white; mercarps rounded or mucronate at apex Anisodontea

19a Mericarps ± divided into 2 compartments by a transverse partition 20
19b Mericarps not divided into 2 compartments 21

20a Plants prostrate, biennial to annual *Modiola
20b Plants erect to decumbent, perennial Anisodontea

21a Lateral walls of mericarps with a clearly demarcated reticulate-fenestrate area in lower third *Sphaeralcea
21b Lateral walls of mericarps smooth or variously ridged to obscurely reticulate-fenestrate Anisodontea

22a Epicalyx of 6-10 bracts Althaea
22b Epicalyx of 3 bracts 23

23a Epicalyx bracts fused at base, broad and leaf-like *Lavatera
23b Epicalyx bracts free to base, mostly linear to lanceolate Malva

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.

Malvaceae on iSpot

David 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!

References:

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.

Identifications

• likely ID 
  Malvaceae by Marion Maclean at 11:12 am 03/03/13

  Confidence: I'm as sure as I can be.
  ID agreements (): 7 people agree with this identification.

  • adriaan_grobler
    
    
  • Wynand Uys
    
    
  • tony rebelo
    
    
  • Riaan Stals
    
    
  • Lee Jones
  • Chris Wahlberg
    
    
  • Andrew Hankey
    
    
  Search Wikipedia for Malvaceae
  Search Encyclopedia of Life for Malvaceae

Species interactions

No interactions present.

Other observations of Malvaceae