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The families of flowering plants

L. Watson and M. J. Dallwitz

Primulaceae Vent.

Including Anagallidaceae Baudo, Lysimachieae (Lysimachiaceae) Juss., Samolineae (Samolaceae) Dum.; excluding Coridaceae, Myrsinaceae, Theophrastaceae.

Habit and leaf form. Herbs; with coloured juice, or non-laticiferous. Perennial (commonly), or annual; with a basal aggregation of leaves, or without conspicuous aggregations of leaves; often rhizomatous, or tuberous. Hydrophytic (Hottonia), or helophytic to xerophytic (many alpine); the hydrophytic Hottonia rooted. Leaves alternate, or opposite, or whorled; when alternate, spiral; petiolate to sessile; non-sheathing; gland-dotted (seemingly infrequently, e.g. in some Anagallis species), or not gland-dotted (mostly); simple. Lamina entire (usually), or dissected; in Hottonia, pinnatifid; pinnately veined, or palmately veined; cross-venulate. Leaves exstipulate. Lamina margins crenate to dentate (usually), or entire. Leaf development not ‘graminaceous’.

Leaf anatomy. The leaf lamina dorsiventral (usually), or centric (in xeromorpic forms). Hydathodes commonly present. Stomata present (except on submerged leaves of the aquatic Hottonia); mainly confined to one surface (abaxial), or on both surfaces; anomocytic. Hairs present (and represented by diverse forms); eglandular and glandular; mostly multicellular. Multicellular hairs uniseriate; branched and simple. Lamina with secretory cavities (commonly), or without secretory cavities. Secretory cavities sometimes containing resin (with red crystalline contents), or containing mucilage; schizogenous, or lysigenous. The mesophyll generally without crystals. Minor leaf veins with phloem transfer cells (variably so, in Anagallis only), or without phloem transfer cells (Anagallis, Auricula, Cyclamen, Dodecatheon, Glaux, Lysimachia, Primula, Samolus, Sodanella).

Axial (stem, wood) anatomy. Secretory cavities present, or absent; with resin, or with mucilage (? - cf. the leaves). Cork cambium present, or absent (cork rarely developed); when present, initially deep-seated, or initially superficial. Nodes unilacunar. Primary vascular tissues variously in a cylinder, without separate bundles, or comprising a ring of bundles, or comprising two or more rings of bundles to consisting of scattered bundles (most species exhibit normal stem anatomy, with widely separated or closely apposed vascular bundles, but in Primula species of the Auricula group, (1) the conventional ring of bundles branches in upper parts of the stem to produce one or more rings or a scattering of bundles or and ‘steles’, and (2) secondary bundles arise in the pericycle; and the stem of the aquatic Hottonia is polystelic, with an ostensible ring of bundles actually comprising stele); collateral. Cortical bundles of forms with normal stem structure, i.e. most, present. Medullary bundles normally absent. Secondary thickening absent (e.g., in most annual Primula spp.), or developing from a conventional cambial ring (usally), or anomalous (in Hottonia and some Primula species, see above).

The vessel end-walls simple. The axial xylem with libriform fibres.

Reproductive type, pollination. Plants hermaphrodite; often heterostylous. Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; when aggregated, in heads, or in umbels, or in panicles. Inflorescences scapiflorous (often), or not scapiflorous; terminal (commonly), or axillary; umbels, panicles or heads. Flowers ebracteolate; small, or medium-sized; regular; (3–)5(–9) merous; cyclic; tetracyclic, or pentacyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla (usually), or sepaline (the corolla absent in Glaux); (6–)10(–18); 2 whorled (usually), or 1 whorled; isomerous. Calyx (3–)5(–9); 1 whorled; gamosepalous; regular; persistent (usually); imbricate, or contorted (e.g. Anagallis); with the median member posterior. Corolla (3–)5(–9); 1 whorled; appendiculate (with staminodal scales), or not appendiculate; gamopetalous; imbricate, or contorted; regular; green, or white, or yellow, or red, or red, or purple, or blue. Petals deeply bifid to bilobed, or entire.

Androecium (3–)5(–9), or 10. Androecial members adnate (to the corolla); free of one another; 1 whorled, or 2 whorled. Androecium exclusively of fertile stamens, or including staminodes (e.g. the antesepalous scales of Samolus and Soldanella). Staminodes when present, 4–6 (alternating with the stamens); when identifiable, external to the fertile stamens (in the sense of being inserted higher on the corolla); when present, petaloid to non-petaloid (‘scales’, or similar to the staminal filaments). Stamens (3–)5(–9); inserted near the base of the corolla tube, or midway down the corolla tube, or in the throat of the corolla tube; isomerous with the perianth; alternisepalous; opposite the corolla members. Anthers dehiscing via pores, or dehiscing via longitudinal slits; introrse; tetrasporangiate. Endothecium developing fibrous thickenings. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with one middle layer. Tapetum glandular. Pollen grains aperturate; (2–)3 aperturate, or 3–10 aperturate; colpate (3–10), or colporate (then usually tricolpate or -colporoidate, sometimes syn- or parasyncolpate); 2-celled (in 6 genera).

Gynoecium supposedly 5 carpelled. Carpels usually isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; eu-syncarpous; superior (usually), or partly inferior (Samolus). Ovary 1 locular (and no evidence of partitions). Gynoecium stylate. Styles 1; attenuate from the ovary; apical. Stylar canal present. Stigmas 1 (simple); dry type; papillate, or non-papillate; Group II type. Placentation free central. Ovules in the single cavity (5–)7–100 (usually ‘many’); ascending; non-arillate; anatropous, or hemianatropous; bitegmic; tenuinucellate. Outer integument contributing to the micropyle. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing only after one has been fertilized, or fusing simultaneously with the male gamete (?). Antipodal cells formed; 3; not proliferating. Synergids elongated. Endosperm formation nuclear. Embryogeny caryophyllad.

Fruit non-fleshy; dehiscent (usually), or indehiscent (rarely); a capsule (usually), or capsular-indehiscent. Capsules valvular, or denticidal (usually five valved and dehiscing by apical teeth), or circumscissile (rarely). Fruit (1–)2–100 seeded (i.e. to ‘many’). Seeds endospermic. Endosperm oily. Seeds with amyloid. Cotyledons 1 (Cyclamen), or 2; semi-cylindric. Embryo achlorophyllous (5/10); straight.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Anagallis, Androsace, Lysimachia, Primula. Anatomy non-C4 type (Androsace, Lysimachia, Samolus). Not cyanogenic. Alkaloids present (rarely), or absent. Arbutin absent. Iridoids not detected. Saponins/sapogenins present, or absent. Proanthocyanidins present (nearly always), or absent (Soldanella); cyanidin, or cyanidin and delphinidin. Flavonols present; kaempferol and quercetin, or kaempferol, quercetin, and myricetin. Ellagic acid present (Hottonia), or absent (usually — 14 species, 7 genera). Aluminium accumulation not found. Sieve-tube plastids S-type.

Geography, cytology. Frigid zone to tropical. Widespread, but centred in the North temperate. X = 5, 8–15, 17, 19, 22.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Primuliflorae; Primulales. Cronquist’s Subclass Dilleniidae; Primulales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; Order Ericales.

Species 1000. Genera 20; Anagallis, Androsace, Ardisiandra, Bryocarpum, Cortusa, Cyclamen, Dionysia, Dodecatheon, Glaux, Hottonia, Kaufmannia, Lysimachia, Omphalogramma, Pelletiera, Pomatosace, Primula, Samolus, Soldanella, Stimpsonia, Trientalis.

General remarks. After analysing a combination of nucleic acid sequences from the chloroplast genes rbcL, ndhF and atpB, Källersjö et al (2000) supported earlier claims that Primulaceae and Myrsinaceae as traditionally circumscribed are paraphyletic, with (e.g.) Anagallis, Ardisiandra, Coris, Lysimachia and Trientalis belonging in myrsinaceous rather than primulaceous clades. Rather than merging all the genera into one supposedly monophyletic family, Anderberg et al (2000) proposed raising Maesa to family rank, and adjusting the contents of Myrsinaceae and Primulaceae. Samolus (with staminodes and semi-inferior overy) may be better referred to Theophrastaceae (q.v.). In the absence of any attempts by modern re-classifiers to prepare the requisite comparative descriptions, the classical family circumscriptions are largely retained here.


. . . Pale primroses,
That die unmarried, ere they can behold
Bright Phoebus in his strength, a malady
Most incident to maids
(‘The Winter’s Tale’, iv., 3)

On her left breast
A mole cinque-spotted like the crimson drops
I’ the bottom of a cowslip
(‘Cymbeline’. For ‘crimson’ read ‘orange’ - a printer’s error?)

In the wood where often you and I
Upon faint primrose-beds were wont to lie
(‘Midsummer Night’s Dream’, i., 1)

Where the bee sucks, there suck I,
In a cowslip’s bell I lie
(‘Tempest’, v., 1)

The flowery May, who from her green lap throws
The yellow cowslip, and the pale primrose
(Milton, ‘Song on May Morning’)

Yellow Lysimachius, to give sweet rest
To the faint shepherd; killing, where it comes,
All busy gnats, and every fly that hums
(Quoted by Ann Pratt, ‘Wild Flowers’ (1857), from ‘The Faithful Shepherdess’)

Illustrations. • Technical details: Cyclamen, Primula. • Technical details: Anagallis, Samolus. • Technical details: Ardisiandra (Thonner). • Anagallis arvensis (2 forms) and Anagallis minumus (as Centunculus): Eng. Bot. 1146, 1147 and 1149, 1867. • Anagallis tenella: Eng. Bot. 1148, 1867. • Cyclamen hederifolium: Eng. Bot. 1136 and 1138, 1867. • Cyclamen neapolitanum: Bot. Reg. XXIV, 49 (1838). • Cyclamen persicum: Bot. Mag. 2, 1788. • Douglasia nivalis: Bot. Reg. 1886 (1836). • Glaux maritima: Eng. Bot. 1150, 1867. • Hottonia palustris: Eng. Bot. 1128, 1867. • Lysimachia thyrsiflora, L. vulgaris, L. ciliata, L. nummularia and L. nemorum: Eng. Bot. 1140–1145, 1867. • Primula vulgaris (Primrose), P. elatior (Oxlip) and P. veris (Cowslip, as P. officinalis): Eng. Bot. 1129–1130, 1867. • Primula veris x P. vulgaris (Common Oxlip) and P. veris x P. elatior: Eng. Bot. 1132 and 1133, 1867. • Primula farinosa and P. scotica: Eng. Bot. 1134 and 1135, 1867. • Primula denticulata: Bot. Reg. 47, 1842. • Primula x venusta: as P. venusta, Bot. Reg. 1983, 1837. • British Primula (B. Ent. compilation). • Samolus repens: flowers (photo). • Samolus repens: habitat (photo). • Samolus valerandi: Eng. Bot. 1151, 1867. • Soldanella alpina: Bot. Mag. 2, 1788. • Lysimachia, Glaux (B. Ent. compilation). • Hottonia, Anagallis, Trientalis, Samolus: B. Ent. compilation). • Leaf hairs of Androsace (3 spp.), Cyclamen and Lysimachia: Solereder, 1908.

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: 19th October 2016.’.