The Families of Angiosperms

L. Watson and M.J. Dallwitz

Rosaceae L.

Including Alchemillaceae J.G. Agardh, Amygdalaceae D. Don, Annulaceae Dulac, Cercocarpaceae J.G. Agardh, Cliffortiaceae Mart., Coleogynaceae J.G. Agardh, Drupaceae S.F. Gray, Dryadeae (Dryadaceae) S.F. Gray, Fragariaceae Rich. ex Nestle., Lindleyaceae J.G. Agardh, Malaceae Small, Neilliaceae Miquel, Pomaceae S.F. Gray, Potentilleae (Potentillaceae) Trautv., Prunaceae Burnett, Rhodotypaceae J.G. Agardh, Sanguisorbeae, (Sanguisorbaceae) Loisel., Spiraeaceae Bertuch, Ulmariae (Ulmariaceae) S.F. Gray

Habit and leaf form. Trees, or shrubs, or herbs; non-laticiferous, without coloured juice. Leaves well developed. Plants autotrophic. The herbs usually perennial; with a basal aggregation of leaves, or without conspicuous aggregations of leaves. Self supporting, or climbing (sometimes); the climbers scrambling. Trees and shrubs leptocaul (often with ‘short shoots’). Helophytic, or mesophytic, or xerophytic. Leaves deciduous (usually), or persistent; alternate (except Rhodotypos); spiral; ‘herbaceous’, or leathery; nearly always petiolate; sheathing, or non-sheathing. Leaf sheaths when leaves sheathing, with free margins. Leaves not gland-dotted; simple, or compound; epulvinate; when compound ternate, or pinnate, or palmate; when pinnate, imparipinnate. Lamina when simple dissected, or entire; pinnately veined (usually), or palmately veined (e.g. Alchemilla); cross-venulate. Leaves stipulate (usually), or exstipulate (in Spiraea etc.). Stipules intrapetiolar (often adnate to the petiole); free of one another; scaly, or leafy. Lamina margins crenate, or serrate, or dentate, or entire (rather infrequently). Vegetative buds scaly. Leaf development not ‘graminaceous’. Domatia occurring in the family (known from 6 woody genera); manifested as pits, or pockets, or hair tufts.

General anatomy. Plants without ‘crystal sand’.

Leaf anatomy. The leaf lamina dorsiventral (usually), or centric (e.g., Crataegus azarolus). Hydathodes present (occasionally), or absent. Mucilaginous epidermis present, or absent. Stomata anomocytic. Minor leaf veins without phloem transfer cells (6 genera, including both herbaceous and woody).

Axial (stem, wood) anatomy. Pith with diaphragms (occasionally), or without diaphragms; homogeneous, or heterogeneous. Cork cambium present, or absent (?); initially deep-seated, or initially superficial. Nodes tri-lacunar (usually), or unilacunar, or penta-lacunar to multilacunar. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. The axial xylem with vessels.

The vessel end-walls simple (nearly always), or scalariform and simple. The vessels without vestured pits. The axial xylem with tracheids (mostly), or without tracheids (Prunoideae); including septate fibres (rarely), or without septate fibres. The parenchyma typically apotracheal, or apotracheal and paratracheal (there being some scanty-paratracheal recorded in a few genera). ‘Included’ phloem absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite (usually). Pollination anemophilous (occasionally, e.g. Poterium), or entomophilous (usually); commonly pollinated by flies; mechanism conspicuously specialized (occasionally), or unspecialized.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in cymes, or in panicles, or in racemes, or in corymbs, or in umbels, or in fascicles. The ultimate inflorescence units when flowers aggregated cymose (usually), or racemose. Inflorescences terminal, or axillary; pseudanthial (occasionally), or not pseudanthial. Flowers small to large; often fragrant; usually regular; cyclic, or partially acyclic. Sometimes the gynoecium acyclic. Flowers tetracyclic to polycyclic. Floral receptacle developing a gynophore (rarely), or with neither androphore nor gynophore; markedly hollowed (Pomoideae, most Prunoideae, some Rosoideae (e.g. Rosa)), or not markedly hollowed (flattish or only slightly concave in Spiraeoideae, convex or swollen in some Rosoideae (e.g. Fragaria, Rubus)). Free hypanthium present (nearly always, the flower generally more or less perigynous), or absent. Hypogynous disk present (often), or absent; intrastaminal.

Perianth with distinct calyx and corolla (usually), or sepaline; (5–)10(–20); 2 whorled (usually), or 1 whorled (when apetalous); usually isomerous. Calyx (3–)5(–10) (usually green and sepaloid); 1 whorled; polysepalous, or gamosepalous; regular; usually imbricate; when determinable, with the median member posterior. Epicalyx present (often, its members alternating with the calyx and seemingly representing its stipules), or absent. Corolla when present, (3–)5(–10); 1 whorled; polypetalous; usually imbricate; regular; white, or yellow, or red, or pink (but not blue).

Androecium (1–)10–100 (usually ‘many’). Androecial members branched (often, in the sense that they are often disposed in pairs), or unbranched; when determinable, ‘at least sometimes’ maturing centripetally (Cronquist 1981); free of the perianth (but usually attached to a hypanthium); free of one another, or coherent; when coherent, often more or less 5 adelphous, or 10 adelphous, or 15 adelphous (etc. — in 5-adelphous whorls); 1–5 whorled (?). Androecium exclusively of fertile stamens (normally), or including staminodes (in cultivars). Staminodes when present, 5–50 (several to ‘many’); external to the fertile stamens; when present, usually petaloid. Stamens (1–)20–100 (usually ‘many’); reduced in number relative to the adjacent perianth to isomerous with the perianth (rarely), or diplostemonous to polystemonous (usually); often with an outer whorl of 10 in five antesepalous pairs; inflexed in bud. Anthers dorsifixed; versatile (mostly), or non-versatile (rarely, e.g. Filipendula); dehiscing via longitudinal slits, or dehiscing via pores (terminal, occasionally); introrse (mostly), or latrorse (e.g. Potentilla); unilocular (sometimes, e.g. Alchemilla), or bilocular; tetrasporangiate. Endothecium developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with more than one middle layer (2 or 3). Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; 3 aperturate (usually), or 4–9 aperturate (?or more, rarely); colporate (or colporoidate, usually), or foraminate (Sanguisorba); hardly ever spinulose; 2-celled (in 14 genera).

Gynoecium 1–50 carpelled. Carpels isomerous with the perianth, or reduced in number relative to the perianth, or increased in number relative to the perianth. The pistil when other than apocarpous, 1 celled, or 2–5 celled. Gynoecium monomerous, or apocarpous, or syncarpous (Maloideae); of one carpel, or eu-apocarpous, or semicarpous, or synovarious (Maloideae); superior, or partly inferior, or inferior (occasionally even combining an inferior ovary with free carpels). Carpel when monomeric or apocarpous non-stylate, or stylate; apically stigmatic, or with a lateral style, or with a gynobasic style; when apocarpous 1–2 ovuled (usually), or 3–10 ovuled (Spiraeoideae). Placentation when apocarpous or one-carpelled apical, or marginal, or basal. Ovary when syncarpous, 2–5 locular (Maloideae). Styles when syncarpous, 2–5; free. Stigmas wet type, or dry type; papillate, or non-papillate; Group II type, Group III type, and Group IV type. Placentation when syncarpous, axile. Ovules 1(–2) per locule; pendulous, or ascending; non-arillate; anatropous (nearly always), or hemianatropous, or campylotropous; unitegmic, or bitegmic; crassinucellate. Outer integument contributing to the micropyle, or not contributing to the micropyle. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization, or fusing simultaneously with the male gamete. Antipodal cells formed; 3; proliferating (sometimes, e.g in Alchemilla), or not proliferating; ephemeral (usually), or persistent. Synergids pear-shaped. Endosperm formation nuclear. Embryogeny asterad.

Fruit fleshy, or non-fleshy; an aggregate (when carpels free), or not an aggregate. The fruiting carpels (when carpels free) commonly coalescing into a secondary syncarp (with small achenes or drupelets), or not coalescing. The fruiting carpel when apocarpous dehiscent, or indehiscent; a follicle, or an achene, or drupaceous, or baccate. Fruit when syncarpous dehiscent (rarely), or indehiscent; a capsule (Lindleyella), or a berry (sometimes in the guise of a pome), or a drupe; enclosed in the fleshy receptacle (or attached to it), or enclosed in the fleshy hypanthium, or without fleshy investment external to the original ovary. The drupes with separable pyrenes, or with one stone. Seeds non-endospermic (nearly always), or endospermic (copiously so in Physocarpus). Perisperm absent. Seeds winged (rarely, e.g. Exochorda), or wingless. Cotyledons 2 (usually expanded and flat). Embryo achlorophyllous (31/64), or chlorophyllous (Rhaphiolepis umbellata); straight, or curved, or bent. Micropyle not zigzag.

Seedling. Germination phanerocotylar (e.g. Crataegus, Malus), or cryptocotylar (e.g. Prunus persica).

Physiology, phytochemistry. C₃. C₃ physiology recorded directly in Fragaria, Malus, Physocarpus, Potentilla, Prunus, Rosa, Rubus, Sorbus, Spiraea. Anatomy non-C₄ type (Potentilla, Prunus, Rosa). Sugars transported as sucrose, or as sugar alcohols + oligosaccharides + sucrose (a quite wide sample found consistently depauperate in oligosaccharides). Inulin not found. Cyanogenic (very commonly), or not cyanogenic. Cynogenic constituents phenylalanine-derived, or leucine-derived. Alkaloids absent (nearly always), or present (very rarely). Arbutin present, or absent. Iridoids not detected. Saponins/sapogenins present, or absent. Proanthocyanidins present, or absent; cyanidin (with the sole exception of a single species of Potentilla). Flavonols present (nearly always); kaempferol and quercetin (nearly always). Ellagic acid variously present (numerous Rubineae, Potentillineae, Dryadineae, Cercocarpeae, Ulmarieae, Sanguisorbieae, Roseae), or absent (numerous Spiraeoideae, Pomoideae, Kerrieae, Prunoideae). Ursolic acid present.

Geography, cytology. Frigid zone to tropical. Cosmopolitan. X = 7–9, 17 (or more).

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

Species almost 3000 (excluding thousands of apomicts!). Genera about 60–100 (depending on delimitation around Geum, Potentilla, Prunus, etc.); Acaena, Adenostoma, Agrimonia, Alchemilla, Amelanchier, Aphanes, Aremonia, Aria, Aronia, Aruncus, Bencomia, Brachycaulos, Cerocarpus, Chaenomeles, Chamaebatia, Chamaebatiaria, Chamaemeles, Chamaemespilus, Chamaerhodos, Cliffortia, Coleogyne, Coluria, Cormus, Cotoneaster, Cowania, Crataegus, Cydonia, Dalibarda, Dichotomanthes, Docynia, Docyniopsis, Dryas, Duchesnea, Eriobotrya, Eriolobus, Exochorda, Fallugia, Farinopsis, Filipendula, Fragaria, Geum, Gillenia, Hagenia, Hesperomeles, Heteromeles, Holodiscus, Horkelia, Horkeliella, Ivesia, Kageneckia, Kelseya, Kerria, Leucosidea, Lindleya, Luetkea, Lyonothamnus, Maddenia, Malacomeles, Malus, Margyricarpus, Mespilus, Neillia, Neviusia, Nuttalia , Oemleria, Orthurus, Osteomeles, Pentactina, Peraphyllum, Petrophytum, Photinia, Physocarpus, Polylepis, Potanina, Potentilla, Poterium, Prinsepia, Prunus, Pseudocydonia, Purshia, Pyracantha, Pyrus, Rhaphiolepis, Rhodotypos, Rosa, Rubus, Sanguisorba, Sarcopoterium, Sibbaldia, Sibiraea, Sorbaria, Sorbus, Spenceria, Spiraea, Spiraeanthus, Stephanandra, Stranvaesia, Taihangia, Tetraglochin, Torminalis, Vauquelinia, Waldsteinia, Xerospiraea.

Economic uses, etc. Edible fruits from Malus spp. (apples), Prunus spp. (apricot, cherry, nectarine, peach, plums, prune, sloe), Cydonia (quince), Pyrus (pear), Eriobotrya (loquat), Rubus (blackberry, boysenberry, loganberry, rasberry), Fragaria (strawberry), Mespilus (medlar); nuts (Prunus — almond); many ornamental trees and shrubs or hedge-plants, e.g. Spiraea, Photinia, Kerria, Cotoneaster, Pyracantha, Crataegus, Sorbus, Rhodotypos, Prunus, Rosa, Potentilla; and some widely naturalized pests (e.g. from Acaena, Crataegus, Cotoneaster, Pyracantha).

Quotations.

The rose is a rose,
And was always a rose.
But the theory now goes
That the apple’s a rose,
And the pear is, and so’s
The plum, I suppose
. . . What will next prove a rose
(Robert Frost, ‘The Rose Family’)

Through the sharp hawthorn blows the cold wind
(‘King Lear’, iii., 4)

The rose looks fair, but fairer we it deem,
For that sweet odour that doth in it live
(Sonnet, liv)

Gather ye rosebuds while ye may,
Old Time is still a-flying
(R. Herrick, ‘To the Virgins, To Make Much of Time’)

O my luve’s like red, red rose
That’s newly sprung in June
(Robert Burns)

The oaks bear mast, the briars scarlet hips
(Timon of Athens, iv., 3)

The time will bring on summer,
When briars shall have leaves as well as thorns,
And be as sweet as sharp
(‘All’s Well That Ends Well’, iv., 4)

The seasons alter; the hoary-headed frosts
Fall in the fresh lap of the crimson rose
(‘Midsummer Night’s Dream’, ii., 2)

What’s in a name? That which we call a rose,
By any other name would smell as sweet
(‘Romeo and Juliet’, ii., 4)

An apple cleft in two is not more twin
Than these two creatures
(‘Twelfth Night’, v., 1)

O, how ripe in show,
Thy lips, those kissing cherries, tempting grow!
(‘Midsummer Night’s Dream’)

When roasted crabs hiss in the bowl,
Then nightly sings the staring owl
(‘Love’s Labour’s Lost’, v., 2 — ‘crab’ = crab-apple)

The sloes appeared as choice as plums
When bitten by the frost
And crabs grew honey in the mouth
When apple time was past
(John Clare 1824–1832, ‘Childhood’ — two species from each of Prunus and Malus)

All other trees are wont to wear
First leaves, then flowers, and last
Their burthen of rich fruit to bear,
When summer’s pride is past;
But thou, so prompt thy flowers to show,
Bear’st but the harsh unwelcome sloe.
(Quoted by Ann Pratt 1857, unattributed — Prunus spinosa)

Their pretty lips with blackberries
Were all besmeared and dy’d
(‘The Children in the Wood’, Roxburghe Ballads ii., 220)

. . . . banks, from whence depend
Rich cymes of Meadow Sweet;
Alas! those creamy clusters lend
A charm, where death and odour meet
(Calder Campbell, quoted by Ann Pratt, ‘Wild Flowers’ (1857) - Filipendula ulmara)

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: 25th April 2024. delta-intkey.com’.

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