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The families of flowering plants

L. Watson and M.J. Dallwitz

Rhamnaceae Juss.

Including Camarandraceae Dulac, Cryptandraceae Barkley, Frangulaceae Lam. & DC., Gouaniaceae, Phylicaceae J.G. Agardh

Habit and leaf form. Trees, shrubs, and lianas, or herbs (Crumenaria). ‘Normal’ plants, or switch-plants; often with the principal photosynthesizing function transferred to stems. Leaves well developed, or much reduced. Self supporting, or climbing; when climbing, tendril climbers, or scrambling. Leptocaul. Mesophytic, or xerophytic. Leaves alternate, or opposite; when alternate, spiral; ‘herbaceous’, or membranous, or modified into spines; petiolate to sessile; non-sheathing; simple. Lamina entire; one-veined, or pinnately veined, or palmately veined; cross-venulate. Leaves stipulate, or exstipulate. Stipules when present, intrapetiolar; free of one another; scaly, or spiny. Domatia occurring in the family (recorded in 4 genera); manifested as pits, or pockets, or hair tufts.

Leaf anatomy. The leaf lamina dorsiventral (usually), or bifacial to centric (occasionally). Mucilaginous epidermis usually present. Stomata present; mainly confined to one surface (usually, abaxial), or on both surfaces; anomocytic (usually), or anisocytic (Cryptandra), or paracytic (e.g., in a few Rhamnus, Colletia and Zizyphus spp.). Hairs present; eglandular; unicellular, or multicellular. Unicellular hairs branched. Multicellular hairs mostly uniseriate; mostly simple. Complex hairs present (notably among Australian genera), or absent; when present, stellate. Adaxial hypodermis present, or absent. Lamina with secretory cavities, or without secretory cavities. Secretory cavities when present, containing mucilage. The mesophyll commonly containing mucilage cells; containing crystals. The crystals druses, or solitary-prismatic (or acicular styloids, in Gouania). Minor leaf veins without phloem transfer cells (Ceanothus, Pomaderris).

Axial (stem, wood) anatomy. Secretory cavities present, or absent; with mucilage. Cork cambium present; initially superficial. Nodes tri-lacunar. Primary vascular tissues in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow.

The wood ring porous to diffuse porous. The vessels small (mostly), or medium (sometimes), or large (rarely); solitary (but never exclusively so), or radially paired, or in radial multiples, or clustered, or in tangential arcs. The vessel end-walls simple. The vessels with vestured pits (rarely), or without vestured pits; with spiral thickening, or without spiral thickening. The axial xylem with tracheids (associated with vessels in radial ‘flames’), or without tracheids; without fibre tracheids; with libriform fibres; including septate fibres (rarely), or without septate fibres. The fibres without spiral thickening. The parenchyma predominantly paratracheal (in most species), or apotracheal (e.g. some Zizyphus spp.). The secondary phloem stratified into hard (fibrous) and soft (parenchymatous) zones (often), or not stratified. ‘Included’ phloem absent. The wood partially storied, or not storied. Tyloses absent (or very rare).

Reproductive type, pollination. Plants hermaphrodite, or monoecious, or androdioecious, or polygamomonoecious (?). Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes, or in heads, or in corymbs, or in panicles. The ultimate inflorescence units cymose. Inflorescences terminal, or axillary; variously cymes, thyrses, corymbs, fascicles, even compound heads in Spyridium and Stenanthemum. Flowers small; regular; (4–)5 merous; cyclic; tetracyclic, or pentacyclic. Floral receptacle when free, markedly hollowed. Free hypanthium present (regardles of whether ovary superior or inferior). Hypogynous disk when stamens hypogynous, present.

Perianth with distinct calyx and corolla, or sepaline (the corolla sometimes lacking); 5, or 8, or 10; 2 whorled (usually), or 1 whorled; isomerous. Calyx (4–)5; 1 whorled; polysepalous, or gamosepalous; regular; valvate. Corolla when present, (4–)5 (often small); 1 whorled; polypetalous; induplicate valvate; regular. Petals clawed (often), or sessile.

Androecium (4–)5. Androecial members free of the perianth (inserted at the mouth of the hypanthium), or adnate (then the filaments adnate to the corolla); free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens (4–)5; isomerous with the perianth; alternisepalous (and usually hooded by the petals, at least when young); opposite the corolla members. Anthers dorsifixed; versatile; dehiscing via longitudinal slits, or dehiscing by longitudinal valves; introrse. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral, or isobilateral. Anther wall initially with more than one middle layer (2); of the ‘basic’ type. Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; usually 3 aperturate; usually colporate; 2-celled (in Scutia and Zizyphus).

Gynoecium (2–)5 carpelled. Carpels isomerous with the perianth, or reduced in number relative to the perianth. The pistil 1 celled, or (2–)3(–5) celled. Gynoecium syncarpous; synovarious to synstylovarious; superior to inferior. Ovary (2–)3(–5) locular, or 1 locular (by abortion). Epigynous disk usually present (when ovary inferior). Gynoecium stylate. Styles 1 (deeply cleft); apical. Stigmas (2–)5; dry type; papillate; Group II type. Placentation when unilocular, basal; when plurilocular, basal. Ovules in the single cavity when unilocular, 1; when 2–5 locular, 1(–2) per locule; funicled to sessile; ascending; when plurilocular, epitropous; with dorsal raphe; when paired, collateral; arillate, or non-arillate; anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type, or Allium-type. Antipodal cells formed; 3 (enlarging, sometimes becoming coenocytic); not proliferating. Synergids hooked (usually with filiform apparatus). Hypostase present, or absent. Endosperm formation nuclear. Embryogeny asterad, or solanad.

Fruit fleshy, or non-fleshy; indehiscent, or a schizocarp. Mericarps when schizocarpic, 2–5. Fruit when non-schizocarpic, a drupe, or a nut. The drupes with separable pyrenes, or with one stone. Fruit sometimes elastically dehiscent. Dispersal unit the mericarp, or the fruit (the latter often specially adapted to wind carriage). Seeds endospermic (thinly), or non-endospermic. Endosperm ruminate (Reynosia), or not ruminate. Embryo well differentiated. Cotyledons 2. Embryo chlorophyllous (4/6); straight.

Seedling. Germination phanerocotylar, or cryptocotylar. Nitrogen-fixing root nodules present (with actinomycetes, in Ceanothus), or absent.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Ceanothus, Rhamnus. Anatomy non-C4 type (Ziziphus). Sugars transported as sucrose (in four genera). Not cyanogenic. Alkaloids present (commonly), or absent. Anthraquinones detected (4 genera); polyacetate derived. Arbutin absent. Iridoids not detected. Saponins/sapogenins present, or absent. Proanthocyanidins present, or absent; when present, cyanidin, or cyanidin and delphinidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent (5 species, 3 genera). Aluminium accumulation not found.

Geography, cytology. Temperate to tropical. Cosmopolitan, except frigid regions. X = (9-)12/13(-23).

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae; Rhamnales. Cronquist’s Subclass Rosidae; Rhamnales. APG III core angiosperms; core eudicot; Superorder Rosanae; fabid. APG IV Order Rosales.

Species 900. Genera about 50; Adolphia, Alphitonia, Alvimiantha, Ampelozizyphus, Auerodendron, Bathiorhamnus, Berchemia, Berchemiella, Blackallia, Ceanothus, Chaydaia, Colletia, Colubrina, Condalia, Crumenaria, Cryptandra, Discaria, Doerpfeldia, Emmenosperma, Gouania, Helinus, Hovenia, Karwinskia, Kentrothamnus, Krugiodendron, Lasiodiscus, Maesopsis, Nesiota, Noltea, Paliurus, Phylica, Pomaderris, Reissekia, Retanilla, Reynosia, Rhamnella, Rhamnus, Sageretia, Schistocarpaea, Scutia, Siegfriedia, Smythea, Spyridium, Talguenea, Trevoa, Trymalium, Ventilago, Ziziphus.

Economic uses, etc. Edible drupes from Ziziphus spp. (jujube, Chinese date, ber or bor). Purgative (cascara sagrada) from Rhamnus purshiana.

Illustrations. • Le Maout and Decaisne: Rhamnus. • Ziziphus baclei: Lindley. • Ceanothus papillosus: Hook. Ic. Pl. 3 (1840). • Ceanothus x pallidus: Bot. Reg. xxvi, 20 (1840). • Ceanothus thyrsiflorus: Bot. Reg. 1844, 38. • Ceanothus x veitchianus: Bot. Mag. 85 (1859). • Colletia infausta: as C. horrida, Bot. Reg. 1776, 1836. • Condalia hookeri, as C. obovata: Hook. Ic. Pl. 3 (1840). • Crumenaria decumbens: Martius, Nova Gen. et Spec. Pl. Brasiliensium 2 (1826). • Cryptandra alpina and Stenanthemum pimeleoides (as Cryptandra): Hooker, Fl. Tasmaniae (1860). • Cryptandra suavis Lindl.: Bot. Reg. 1844, 56. • Nesiota elliptica: Hook. Ic. Pl. 11 (1867–71). • Rhamnus catharticus and Frangula alnus (as Rhamnus frangula): Eng. Bot. 318–319, 1864. • Frangula alnus (B. Ent.). • Sageretia rugosa, as S. ferruginea: Hook. Ic. Pl. 18 (1887). • Smythea macrocarpa: Hook. Ic. Pl. 16 (1887). • Spyridium gunnii (as Cryptandra): Hooker, Fl. Tasmaniae (1860). • Ziziphus affinis: Hook. Ic. Pl. 16 (1886). • Ziziphus rugosa: Wight’s Figs. of Indian Plants 2 (1843).

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or 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). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 15th April 2018.’.