Neotropical Meliaceae

Description

Trees, treelets or rarely shrubs; plants monoecious, dioecious or polygamous.  Buds protected by a cluster of scale-leaves or naked.  Stipules absent.  Leaves spirally arranged, usually pinnate, with or without a terminal leaflet, often with a terminal bud showing intermittent growth, less frequently trifoliolate or unifoliolate, rarely digitate or bipinnate; leaflets usually entire, rarely lobed, serrate, crenate or spinous; venation usually eucamptodromous, less frequently brochidodromous, rarely craspedodromous; indumentum usually simple, less frequently of stellate, malpighiaceous or dibrachiate hairs, or peltate scales.  Inflorescence usually axillary or in axils of scale leaves, less frequently ramiflorous or cauliflorous, usually paniculate with cymose branchlets (thyrsoid), less frequently racemose, spicate or fasciculate, or inflorescence reduced to 1-2 flowers.  Flowers actinomorphic, bisexual or unisexual; rudiments of opposite sex well-developed in unisexual flowers; calyx usually shallowly or deeply 3-5(-7)-lobed, less frequently truncate or with free sepals; aestivation usually open, less frequently imbricate, rarely quicuncial; petals 3-7, free or partially united, aestivation usually imbricate or valvate, less frequently quincuncial or contorted; filaments rarely completely free, usually partly or completely united to form a staminal tube, with or without appendages; staminal tube 0.75-14 mm long, urceolate, cyathiform or cylindrical, margin entire or with small appendages alternating with anthers or rarely opposite them; anthers (4-)5-10(-14), hairy or glabrous, inserted apically on filaments or on margin of staminal tube, or within throat of staminal tube and partially or completely included, connective rarely produced to form a long thread-like appendage; antherodes in female flowers smaller, slender, not dehiscing or producing pollen; nectary (disk) intrastaminal, stipitate, annular, patelliform, cyathiform or absent, free from or partly fused to base of staminal tube or ovary.  Ovary 2-13- locular, loculi uniovulate, biovulate or multiovulate; placentation axile; ovules collateral, superposed or biseriate; style-head capitate, conical, lobed or discoid.  Pistillode in male flowers smaller, usually with a more slender style, but often with well-developed abortive ovules.  Fruit a loculicidal, septicidal or septifragal capsule or rarely a drupe.  Seed either winged and then usually attached to a large woody columella, or unwinged and then usually with a fleshy arillode or sarcotesta, rarely with a corky or woody sarcotesta, usually exendospermous, occasionally endospermous.  Embryo with plano-convex or flat, collateral, superposed or rarely oblique cotyledons;  radicle usually superior, less frequently abaxial, included, extending to surface or long-exserted.

Notes on delimitation

See the APG website.

Distribution in the Neotropics

• Azadirachta A.Juss.: introduced widespread.
• Aphanamixis Blume: introduced Brazil, Cuba.
• Cabralea A.Juss.: native Costa Rica to Argentina.
• Carapa Aubl.: native Guatemala to Brazil, West Indies.
• Cedrela P.Browne: native Mexico to Argentina, West Indies.
• Guarea Allam. ex L.: native Mexico to Argentina, West Indies.
• Khaya A.Juss.: introduced Cuba, French Guiana.
• Melia L.: introduced, widespread.
• Ruagea Karsten: native Guatemala to Bolivia.
• Sandoricum Cav.: introduced Costa Rica. Schmardaea Karsten: native Venezuela to Peru.
• Swietenia Jacq.: native Mexico to Bolivia and Brazil, West Indies.
• Toona (Endl.)M. Roemer: introduced as plantation tree.
• Trichilia P.Browne: native Mexico to Argentina, West Indies.

Other important characters

• Pinnate leaves.
• Actinomorphic flowers; stamens united in a staminal tube, with anthers inserted either on the margin or within the throat; intrastaminal nectary -disk present.
• Fruit a loculicidal, septifragal or septicidal capsule; seeds fleshy with an arillode or sarcotesta, or dry and then winged.

Key differences from similar families

The families below differ from Meliaceae in the following characters:

• Sapindaceae - leaf rhachis ends in aborted tip, petals often clawed and with a scale-like appendage inside, nectary-disk outside or opposite the stamens,  nectary-disk and androecium often zygomorphic, stamens free.
• Anacardiaceae - twigs with transparent or milky exudate often caustic, which turns black on drying, twigs usually reddish or pink (fresh), stamens free, fruit a drupe or samara.
• Burseraceae - bark, twigs and leaves with resinous (turpentine) odour when crushed, bark slash with colourless or whitish resinous exudate, stamens free, fruit a drupe or of several free or fused pyrenes.
• Simaroubaceae - stamens free, often with an appendage on the filament, ovary of free or only partly united carpels, with several styles, fruit often apocarpous.

Number of genera

• 14 genera in the Neotropics.

Useful tips for generic identification

Key to the American Genera of Meliaceae (including those introduced (*) and sometimes naturalized)

1.  Loculi with 1-2 ovules, fruit a loculicidal capsule or drupe (subfamily Melioideae) … 2
1.  Loculi with 3 to many ovules, these biseriate; fruit a septifragal capsule (subfamily Swietenioideae) … 9

2.  Leaves 2-3 pinnate. … Melia*.
2.  Leaves usually pinnate, less frequently 1-3-foliolate or rarely digitate … 3

3.  Anthers inserted at apex of filaments or on margin of staminal tube … Trichilia
3.  Anthers inserted within throat of staminal tube … 4

4.  Petals 3; staminal tube globose with a constricted throat; nectary absent … Aphanamixis*
4.  Petals 4-7; staminal tube shortly cylindrical, throat not constricted; nectary in the form of a stout stipe, usually expanded to form a collar beneath ovary or cyathiform, rarely tubular or annular … 5

5.  Nectary cyathiform or tubular … 6
5.  Nectary stipitate, often expanded at apex to form a collar beneath ovary, rarely annular or absent … 7

6.  Fruit a fleshy drupe; nectary tubular; stigma 4-5-lobed … Sandoricum*
6.  Fruit a loculicidal capsule; nectary cyathiform; stigma discoid … Cabralea

7.  Loculi with 2 collateral ovules; style-head 3-lobed; fruit a 1(-2)-seeded drupe … Azadirachta*
7.  Loculi with 1-2 superposed ovules; style-head discoid; fruit a capsule … 8

8.  Sepals free, quincuncial, ciliate; petals quincuncial; leaves often imparipinnate with terminal leaflet, never with a terminal bud; ovary glabrous … Ruagea
8.  Sepals partially united, aestivation open, hardly ever ciliate; petals nearly always valvate, rarely imbricate or contorted; leaves nearly always with a terminal bud showing intermittent growth or terminal dormant bud, rarely paripinnate, very rarely unifoliolate; ovary usually pubescent or strigose … Guarea

9.  Staminal tube of completely united filaments; anthers 8-10(-12), inserted within throat of staminal tube; nectary annular or reduced to a short stipe below ovary, never in the form of an androgynophore … 10
9.  Stamens 5, filaments free but adnate to an androgynophore below; anthers inserted apically on filaments … 13

10.  Leaflet margin crenate, serrate, or dentate; anthers bearing a long thread-like appendage; nectary represented by a short unexpanded stipe beneath ovary; capsule ellipsoid or fusiform, thin-walled, fragile … Schmardaea
10.  Leaflet margin entire; anthers without a thread-like appendage; nectary annular or patelliform; capsule thick-walled, ovoid to spheroidal, leathery or woody … 11

11.  Ovules 3-8 in each loculus; seed large, angular, unwinged, surrounded by a thick woody sarcotesta … Carapa
11.  Ovules 12-16 in each loculus; seeds small, winged, without a woody sarcotesta … 12

12.  Capsule globose, subglobose, or trigonous, not or scarcely longer than broad; seeds orbicular to suborbicular, winged all the way around … Khaya*
12.  Capsule oblong ovoid or obovoid, elongate, at least twice as long as broad; seed with a single terminal wing … Swietenia

13.  Seeds winged below, attached by the seed towards apex (distal end) of central columella; androgynophore column-shaped, longer than ovary … Cedrela
13.  Seeds winged at both ends, or if with one wing then attached by seed-end towards base of central columella (proximal end) and winged above; androgynophore cushion-shaped, shorter than or equally ovary … Toona*
 

Notable genera and distinguishing features

• Cabralea: differs from Guarea in leaves lacking terminal bud and glandular-punctate and -striate; flower with cyathiform nectary-disk, sepals imbricate.
• Carapa: stamens united; large septifragal capsule with large corky seeds which float in water.Cedrela: stamens free; septicidal capsule with dry winged seeds.
• Guarea: leaves with a dormant bud(with intermittent growth) between the apical pair of leaflets; stamens inserted inside the throat of the staminal tube; loculicidal capsule, seeds fleshy with a sarcotesta.
• Melia: leaves bipinnate, leaflets serrate or crenate; fruit a drupe.
• Ruagea: differs from Guarea in leaves lacking terminal bud, imbricate sepals.
• Schmardaea: leaflets crenate, serrate or dentate; anthers with connective produced into a long thread-like appendage.
• Swietenia: stamens united; large septifragal capsule with dry winged seeds.
• Trichilia: stamens with anthers at apex of filaments or on margin of staminal tube; loculicidal capsule, seeds fleshy, arillate.

Status

Important literature

Pennington, T.D. & Gorts-van Rijn, A.R.A. 1984. Meliaceae, pp. 519-569. In: Stoffers, A.L. & Lindeman, J.C. (eds.), Fl. Suriname. Van Eedenfonds, Utrecht.

How to cite

Pennington, T.D. (2009). Neotropical Meliaceae. In: Milliken, W., Klitgεrd, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Meliaceae.htm.