The families of flowering plants

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L. Watson and M. J. Dallwitz

Araliaceae Juss.

Including Botryodendraceae J.G. Agardh, Myodocarpaceae Doweld; excluding currently Umbelliferae-Hydrocotyloideae.

Habit and leaf form. Trees (mostly, usually of moderate size but sometimes very large, with Peekeliopanax reaching 40 m high), or ‘arborescent’, or shrubs (including some woody epiphytes), or lianas, or herbs (Panax, Stilbocarpa, some species of Aralia, etc.); non-laticiferous and without coloured juice; bearing essential oils, or without essential oils; resinous. ‘Normal’ plants (nearly always), or switch-plants (e.g., with the linear leaves of Lilaeopsis and Oxypolis interpretable as highly modified pinnately compound leaves, with nodal appendages representing pinnae transformed into hydathodes). Plants autotrophic. Perennial; without conspicuous aggregations of leaves. Self supporting, or epiphytic, or climbing; when climbing stem twiners, or root climbers. Pachycaul (nearly always, mostly large-leaved and thick-stemmed), or leptocaul (e.g., in Pseudopanax, in which long- and short-shoots are distinguishable). Heterophyllous (sometimes, e.g. Hedera helix, where progression from lobed to entire leaves reflects irreversible shoot maturation), or not heterophyllous. Leaves medium-sized to very large (to over 3 m in Aralia), or small (rarely, but only 1–2 cm in Pseudopanax anomalum); alternate (nearly always), or opposite (Cheirodendron, Eremopanax), or whorled (Panax); spiral (mostly), or distichous (rarely), or four-ranked (rarely); commonly leathery; petiolate (usually), or subsessile; more or less sheathing (usually), or non-sheathing. Leaf sheaths with free margins. Leaves gland-dotted, or not gland-dotted; aromatic, or without marked odour; simple (mostly), or compound; not peltate (usually), or peltate (some Harmsiopanax spp.); when compound, ternate, or pinnate, or palmate, or multiply compound. Lamina when simple, dissected (usually), or entire; pinnatifid, or palmatifid; pinnately veined, or palmately veined. Leaves stipulate, or exstipulate. Stipules when present, intrapetiolar (often adnate to and scarcely distinguishable from the base of the petiole). Vegetative buds scaly. Leaf development not ‘graminaceous’; leaves becoming compound from primordial lobes.

Leaf anatomy. The leaf lamina dorsiventral (usually), or bifacial to centric. Stomata present; usually mainly confined to one surface (mostly abaxial); paracytic (usually), or anomocytic. Hairs present (not always numerous, but of diverse types, with shaggy, 2-armed, tufted, stellate, and peltate forms recorded). Complex hairs present (usually), or absent; commonly stellate. Adaxial hypodermis present (very commonly), or absent. Lamina or more often canals with secretory cavities. Secretory cavities presumably containing resin, or containing oil, containing mucilage, containing resin, and containing latex (? - cf. those of the stems); schizogenous. The mesophyll not containing mucilage cells (seemingly lacking secretory cells of any sort). Minor leaf veins without phloem transfer cells (Aralia, Hedera).

Axial (stem, wood) anatomy. Secretory cavities or more often canals universally present; with resin (presumably), or with oil, with resin, with mucilage, and with latex (i.e., with imprecise references to oily, resinous, gummy and occasionally milky contents). Cork cambium present; initially superficial. Nodes penta-lacunar to multilacunar (mostly), or tri-lacunar (rarely). Primary vascular tissue generally comprising a ring of bundles (at first, separated by wide rays), or in a cylinder, without separate bundles (subsequently), or comprising two or more rings of bundles, or consisting of scattered bundles (the conventional ring often accompanied by additional cortical and/or medullary circles of bundles, and occasionally by scattered medullary bundles); collateral. Internal phloem absent. Cortical bundles present (commonly), or absent. Medullary bundles present (often), or absent. Secondary thickening usually developing from a conventional cambial ring (? - no reference to anomalous secondary thickening having been found).

The wood ring porous to diffuse porous. The vessels small to medium; variously radially paired, in radial multiples, clustered, and in tangential arcs. The vessel end-walls simple (usually), or scalariform (often with few bars), or scalariform and simple. The vessels without vestured pits; with spiral thickening, or without spiral thickening. The axial xylem without tracheids; without fibre tracheids; with libriform fibres; usually including septate fibres (especially around the vessels). The fibres without spiral thickening. The parenchyma usually paratracheal (only, often very sparse). ‘Included’ phloem absent. The wood not storied. Tyloses present, or absent.

Reproductive type, pollination. Plants hermaphrodite, or monoecious, or andromonoecious, or gynomonoecious, or dioecious, or polygamomonoecious.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in spikes, in heads, and in umbels (with umbels less prevalent than in the Umbelliferae). The ultimate inflorescence units cymose (mostly), or racemose (represented in probably no more than 10 genera). Inflorescences terminal, or axillary, or leaf-opposed (though appearing lateral, rarely - e.g. in Mackinlaya, and sometimes genuinely lateral in Aralia, Schefflera and Stilbocarpa), or epiphyllous (rarely); a few genera exhibiting racemes, most with umbels or heads, often massed into compound inflorescences. Flowers calyptrate (rarely), or not calyptrate; usually more or less 5 merous; cyclic.

Perianth with distinct calyx and corolla, or petaline; (6–)10(–24); 1 whorled (only in Meryta, where the calyx is entirely lacking), or 2 whorled; when two-whorled, isomerous, or anisomerous. Calyx when present, 3–5(–12); 1 whorled; when present, polysepalous, or gamosepalous; entire, or lobulate, or blunt-lobed, or toothed (sometimes reduced to small teeth or a mere rim); often open in bud. Corolla (3–)5(–13) (the interpretation sometimes complicated by partially divided or lobed segments); 1 whorled; commonly alternating with the calyx (most genera having five calyx components alternating with five petals, but numerous exceptions occur); polypetalous, or partially gamopetalous, or gamopetalous (and sometimes connate at the base); calyptrate (rarely), or not calyptrate; imbricate (in the Aralieae), or valvate; regular; typically rather fleshy, or not fleshy. Petals clawed (Mackinleyeae), or sessile (usually with broad bases inserted around the whole circumference of the upper part of the ovary).

Androecium (3–)5(–12), or 10–100 (the same number as the corolla members, twice the number, or ‘many’). Androecial members free of the perianth; all equal; free of one another. Androecium exclusively of fertile stamens. Stamens variously (3–)5(–12), or 10–100; isomerous with the perianth (usually), or diplostemonous, or polystemonous; alternating with the corolla members (usually, when equalling them in number), or opposite the corolla members; inflexed in bud; filantherous (the filaments usually fleshy and short). Anthers dorsifixed; not becoming inverted during development; dehiscing via longitudinal slits; introrse; tetrasporangiate (nearly always, but occasionally appearing bisporangiate by early fusion dring development), or multisporangiate (8 in Octotheca and Dizygotheca). Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with one middle layer, or initially with more than one middle layer. Tapetum glandular. Pollen grains aperturate; 3 aperturate (mostly), or 2 aperturate, or 4 aperturate, or 6 aperturate; colporate (mostly), or colpate, or rugate; 3-celled.

Gynoecium (1–)2–5(–100) carpelled (about 20 in species of Gastonia, Plerandra and Reynoldsia, up to 100 in Tupidanthus). Carpels reduced in number relative to the perianth to increased in number relative to the perianth. The pistil (1–)2–5(–100) celled. Gynoecium syncarpous (nearly always), or monomerous (rarely, at least ostensibly so); of one carpel (in Diplopanax, and ostensibly so in Arthrophyllum and Eremopanax), or synovarious to eu-syncarpous (nearly always, the styles often constituting a solid or sometimes hollow stylopodium); partly inferior to inferior, or superior (recorded only in two species of Tetraplasandra). Carpel when monomeric, i.e. rarely, ostensibly 1 ovuled (but with a second abortive one). Ovary 1–100 locular. Locules without ‘false septa’. Epigynous disk present (with a nectariferous disk between the stylopodium and the stamens). Gynoecium more or less stylate. Styles variously 1–100; when two or more, free, or partially joined; apical. Stigmas usually present, as a frequently double stigmatic crest capping the stylopodium; wet type, or dry type; papillate; Group II type and Group III type. Placentation when unilocular, i.e. rarely, parietal to apical; when bi- or plurilocular, i.e. nearly always, axile to apical. Ovules in the single cavity 1–2 (with one abortive); 1 per locule, or 1–2 per locule (usually with a second abortive one); pendulous; epitropous; with ventral raphe; anatropous; unitegmic; crassinucellate (mostly), or tenuinucellate. Endothelium differentiated. Polar nuclei fusing prior to fertilization. Antipodal cells formed, or not formed (then the three nuclei degenerating early); when formed, 3; not proliferating. Synergids pear-shaped. Hypostase present, or absent. Endosperm formation nuclear.

Fruit fleshy, or non-fleshy; indehiscent, or a schizocarp (then cf. Umbelliferae). Mericarps when schizocarpic, 2–5(–100) (?). Fruit when non-schizocarpic, a berry, or a drupe. The drupes with separable pyrenes, or with one stone (as many pyrenes as the locules). Gynoecia of adjoining flowers combining to form a multiple fruit, or not forming a multiple fruit. Seeds endospermic. Endosperm ruminate (e.g. Hedera), or not ruminate; oily. Cotyledons 2. Embryo achlorophyllous (2/3).

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Hedera. Sugars transported as sucrose (Brassaia, Silibertia). Inulin not found (umbelliferose recorded). Not cyanogenic. Polyacetylenes recorded (falcarinone). Alkaloids present, or absent. Arbutin absent. Iridoids not detected (in any of the members screened, discounting a spurious record for Hedera and with Aralidium and Diplopanax excluded). Saponins/sapogenins present. Proanthocyanidins absent. Flavonols present, or absent; quercetin, or kaempferol and quercetin. Ellagic acid absent (5 species, 5 genera). Aluminium accumulation not found. Sieve-tube plastids S-type.

Geography, cytology. Temperate (a few), or sub-tropical to tropical (mainly). Widespread, but especially Indomalaya and tropical America. X = 11, 12(+).

Taxonomy. Subclass Dicotyledonae; Tenuinucelli (or borderline, but uncertainties may reflect a few misplaced genera). Dahlgren’s Superorder Araliiflorae; Araliales. Cronquist’s Subclass Rosidae; Apiales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; campanulid; Order Apiales.

Species 700. Genera 49; Anakasia, Apiopetalum, Aralia, Arthrophyllum, Astrotricha, Boninofatsia, Brassaiopsis, Cephalaralia, Cheirodendron, Cromapanax, Cuphocarpus, Cussonia, Delarbrea, Dendropanax, Eleutherococcus, Fatsia, Gamblea, Gastonia, Harmsiopanax, Hedera, Heteropanax, Hunaniopanax, Kalopanax, Mackinlaya, Macropanax, Megalopanax, Merrilliopanax, Meryta, Motherwellia, Munroiodendron, Myodocarpus, Oplopanax, Oreopanax, Osmoxylon, Panax, Pentapanax, Polyscias, Pseudopanax, Pseudosciadium, Reynoldsia, Schefflera, Sciadodendrom, Seemannaralia, Sinopanax, Stilbocarpa, Tetrapanax, Tetraplasandra, Trevesia, Woodburnia. Diplopanax has been transferred to the cornaceous alliance.

General remarks. This family exemplifies the well known difficulties in distributing certain Dicot families not only between Dahlgren’s Araliiflorae and Corniflorae, but also between the higher level groupings Crassinucelli and Tenuinucelli; this despite the fact that the latter evidently represent a major divergence in the Dicot line of descent (cf.Young and Watson 1970, Chase et al. 1993). In terms of the data compiled for this package, other than two ‘esoteric characters’ reflecting limited sampling (wet/dry stigmas, occurrence of septate wood fibres), there are no absolute differences between Araliaceae and Umbelliferae: they are distinguishable only in having the states of overlapping characters expressed in different proportions. This does not mean of course that the families should be merged, because the names permit useful predictive generalization. On the other hand, it does support S.M. Walters’s (1960) entertaining contention regarding the historical origins of useful family circumscriptions; viz., that that if formal taxonomy had originated in the southern hemisphere, the Umbelliferae would now be a subfamily of the Araliaceae.

Economic uses, etc. Some cultivated ornamentals, including notable houseplants, e.g. Hedera, Aralia, Polyscias, Schefflera, Fatsia. Ginseng roots from Panax quinquefolius, Chinese rice paper from the pith of Tetrapanax papyriferus.

Illustrations. • Technical details, from Thonner (Cussonia). • Technical details (Hedera, Reynoldsia). • Technical details (Hedera helix: Lindley). • Technical details (Aralia edulis, Gastonia). • Hedera helix (B. Ent.). • Trevesia palmata: Bot. Reg. 894, 1825. • Leaf hairs (Solereder, 1908).

Quotations

Sleep thou, and I will wind thee in my arms,
. . . . the female ivy so
Enrings the barky fingers of the elm
(‘Midsummer Night’s Dream’, iv., 1)

Oh, falsely they accuse me,
Who say I seek to check
The growing sapling’s flourishing; —
I better love to deck
The dead or dying branches
With all my living leaves.
’Tis for the old and wither’d tree,
The Ivy garlands weaves.
Calder Campbell, quoted by Ann Pratt 1857)


This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 19th October 2013. http://delta-intkey.com’.

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