The Families of Flowering Plants

L. Watson and M. J. Dallwitz

Malvaceae Juss.

Including Hibiscaceae J.G. Agardh, Philippodendraceae Endl., Plagiantheae (Plagianthaceae) J.G. Agardh

Excluding Bombacaceae, Byttneriaceae, Sterculiaceae, Tiliaceae

Habit and leaf form. Herbs and shrubs, or trees (a few). Mostly ‘normal’ plants, or switch-plants (Lawrencia helmsii); the halophytic L. helmsii ‘cactoid’ (at least, having cactoid lateral branches). Mesophytic, or xerophytic. Leaves alternate; spiral; petiolate; non-sheathing; simple. Lamina dissected (usually), or entire; when dissected, palmatifid; palmately veined; cross-venulate. Leaves usually stipulate; without a persistent basal meristem.

Leaf anatomy. Hydathodes present (occasionally), or absent. Mucilaginous epidermis present (commonly, sometimes penetrating into the mesophyll), or absent. Stomata present; commonly on both surfaces; anomocytic. Hairs present; eglandular, or eglandular and glandular. Complex hairs commonly present; stellate (very commonly), or peltate.

Adaxial hypodermis present, or absent. Lamina dorsiventral (usually), or isobilateral to centric (rarely); with secretory cavities, or without secretory cavities. The mesophyll containing mucilage cells, or not containing mucilage cells; with sclerencymatous idioblasts, or without sclerenchymatous idioblasts. Minor leaf veins without phloem transfer cells (4 genera).

Stem anatomy. Secretory cavities present (usually, in cortex and pith), or absent; with mucilage (usually accompanied by mucilage cells). Cork cambium present; initially superficial. Nodes tri-lacunar, or penta-lacunar, or multilacunar. Cortical bundles absent. Medullary bundles present (Abutilon), or absent. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones. Xylem with fibre tracheids, or without fibre tracheids; with libriform fibres, or without libriform fibres; with vessels. Vessel end-walls simple. Vessels without vestured pits. Tile cells present (Durio and Pterospermum types). Wood partially storied (VP, VPR); parenchyma apotracheal, or paratracheal. Sieve-tube plastids S-type.

Reproductive type, pollination. Plants hermaphrodite (usually), or dioecious (rarely), or polygamomonoecious (rarely). Floral nectaries present (these trichomatic). Entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes. The terminal inflorescence unit cymose. Inflorescences compound cymose, composed of cincinni. Flowers small to large; regular to somewhat irregular. The floral irregularity involving the perianth (the petals often asymmetrical), or involving the perianth and involving the androecium. Flowers cyclic. Free hypanthium absent. Hypogynous disk absent.

Perianth with distinct calyx and corolla; 10; 2 whorled; isomerous. Calyx 5; 1 whorled; polysepalous, or gamosepalous (basally); regular; valvate. Epicalyx present (often, representing aggregated bracteoles or stipules?), or absent. Corolla 5; 1 whorled; polypetalous (but often seeming gamopetalous at first sight, through association with the androecial tube); contorted, or imbricate; often asymmetrical.

Androecium (5–)15–100 (i.e. usually ‘many’). Androecial members branched (usually, involving the inner whorl of stamens, the androecium originating from relatively few trunk bundles); when many (i.e. usually), maturing centrifugally; adnate (to the petals); coherent (the filaments forming a tube); 1 adelphous (the tube attached to the petals); 1 whorled (usually, the outer whorl being supposedly absent). Androecium exclusively of fertile stamens (or rather, half-stamens, each having only a half anther). Stamens (5–)15–50; isomerous with the perianth to polystemonous. Anthers dehiscing via longitudinal slits; introrse; unilocular; bisporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or decussate. Anther wall initially with one middle layer; of the ‘dicot’ type. Tapetum amoeboid. Pollen polysiphonous; shed as single grains. Pollen grains aperturate; 3–4 aperturate, or 5–100 aperturate (or more, in Althea); colporate, or foraminate, or rugate; usually spinulose; 2-celled.

Gynoecium (1–)5(–100) carpelled (i.e. sometimes ‘many). The pistil 1–5(–100) celled (— occasionally ‘many’). Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary (1–)5(–100) locular (occasionally many-locular). Locules secondarily divided by ‘false septa’ (in Malopeae only, these horizontal, resulting in one-ovuled segments), or without ‘false septa’ (usually); in Malopeae each divided horizontally into one-ovulate locelli, or not horizontally divided (usually). Styles (1–)5(–20); free to partially joined; apical. Stigmas dry type; papillate, or non-papillate; Group II type. Placentation axile. Ovules 1–50 per locule (i.e. to ‘many’); ascending (usually), or pendulous (sometimes); with ventral raphe to with dorsal raphe; anatropous to campylotropous; bitegmic; crassinucellate. Outer integument contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; proliferating (often, forming up to 20 cells), or not proliferating (often); ephemeral, or persistent. Synergids pear-shaped, or hooked (sometimes with filiform apparatus). Endosperm formation nuclear. Embryogeny asterad.

Fruit non-fleshy (usually), or fleshy; dehiscent, or indehiscent, or a schizocarp. Mericarps when schizocarpic, (1–)5(–100); comprising follicles, or comprising nutlets. Fruit a capsule (usually), or a berry (Malvaviscus). Capsules loculicidal. Seeds endospermic. Endosperm oily. Seeds conspicuously hairy, or not conspicuously hairy. Cotyledons 2. Embryo chlorophyllous (7/9), or achlorophyllous (2/2); usually curved. Micropyle zigzag.

Seedling. Germination phanerocotylar.

Physiology, biochemistry. Cyanogenic, or not cyanogenic. Alkaloids present (?), or absent (mostly). Iridoids not detected. Proanthocyanidins present, or absent; cyanidin (usually), or cyanidin and delphinidin. Flavonols present, or absent; kaempferol, or quercetin, or kaempferol and quercetin. Ellagic acid absent (11 species, 10 genera). Saponins/sapogenins absent. Aluminium accumulation not found. Sugars transported as sucrose (Abutilon, Hibiscus, Montezuma). C₃. C₃ physiology recorded directly in Abutilon, Gossypium, Malva, Sida, Sphaeralcea. Anatomy non-C₄ type (Gossypium, Hibiscus, Malva, Sphaeralcea, Thespesia).

Geography, cytology. Frigid zone to tropical. Cosmopolitan tropical and temperate, also Iceland. X = 6–17(+), 20(+).

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Malvales. Cronquist’s Subclass Dilleniidae; Malvales. APG (1998) Eudicot; core Eudicot; Rosid; Eurosid II; Malvales. Species 1000. Genera about 100; Abelmoschus, Abutilon, Abutilothamnus, Acaulimalva, Alcea, Allosidastrum, Allowissadula, Althaea, Alyogyne, Anisodontea, Anoda, Anotea, Asterotrichion, Bakeridesia, Bastardia, Bastardiastrum, Bastardiopsis, Batesimalva, Billieturnera, Briquetia, Callirhoe, Calyculogigas, Calyptraemalva, Cenocentrum, Cephalohibiscus, Cienfuegosia, Codonochlamys, Corynabutilon, Cristaria, Decaschistia, Dendrosida, Dicellostyles, Dirhamphis, Eremalche, Fioria, Fryxellia, Gaya, Goethea, Gossypioides, Gossypium, Gynatrix, Hampea, Helicteropsis, Herissantia, Hibiscadelphus, Hibiscus, Hochreutinera, Hoheria, Horsfordia, Howittia, Humbertianthus, Humbertiella, Iliamna, Julostylis, Jumelleanthus, Kearnemalvastrum, Kitaibela, Kokia, Kosteletzkya, Krapovickasia, Kydia, Lagunaria, Lavatera, Lawrencia, Lebronnecia, Lecanophora, Lopimia, Macrostelia, Malachra, Malacothamnus, Malope, Malva, Malvastrum, Malviscus, Malvella, Megistostegium, Meximalva, Modiola, Modiolastrum, Monteiroa, Napaea, Nayariophyton, Neobaclea, Neobrittonia, Nototriche, Palaua, Pavonia, Peltaea, Periptera, Perrierophytum, Phragmocarpidium, Phymosia, Plagianthus, Radyera, Rhynchosida, Robinsonella, Rojasimalva, Senra, Sida, Sidalcea, Sidastrum, Sphaeralcea, Symphyochlamys, Tarasa, Tetrasida, Thespesia, Urena, Urocarpidium, Wercklea, Wissadula.

Bayer et al. expand Malvaceae to include Bombacaceae, Sterculiaceae and Tiliaceae, consequent on a combined analysis of plastid atpB and rbcL DNA sequences.

Economic uses, etc. Gossypium seed supplies commercial cotton, pulp and oil. ‘Rosella fruit’ (Jamaica sorrel) is the fleshy calyx and bracts of Hibiscus sabdariffa, while ‘ochra’ (‘okra’) is the young fruits of Hibiscus esculentus. Some pot-herbs (Malva parviflora), and many ornamentals.

Illustrations. • Malva sylvestris. • Malva moschata. • Technical details (Malva, Lavatera). • Technical details (Abutilon, Malva). • Technical details (Althaea, Plagianthus).

Quotations

GONZALO: Had I plantation of this isle, my lord —
ANTONIO: He’d sow’t with nettle-seed.
SEBASTIAN: Or docks or mallows.
(‘Tempest’ ii, 1 — Malva sylvestris being notoriously untidy)