Family Sarraceniaceae

Sarraceniaceae Dum.

Including Diphylleiaceae Schultz-Schultzenst. (p.p.)

Habit and leaf form. Herbs. ‘Normal’ plants to switch-plants; often partially phyllodineous. Plants ‘carnivorous’. Trapping mechanism passive. The traps consisting of ‘pitchers’ (cf. Nepenthaceae). Perennial; with a basal aggregation of leaves; rhizomatous. Helophytic (in sunny, marshy places). Heterophyllous, or not heterophyllous (sometimes producing reduced, pitcherless leaves (phyllodes) late in the season). Leaves medium-sized; alternate; spiral; petiolate (shortly so, unless the elongate pitcher represents petiole and the lid a reduced blade); non-sheathing; with a ventral laminar ridge or wing on the elongate pitcher, and a relatively small flattened abaxial apical projection forming a hood; simple; epulvinate. Lamina cross-venulate. Leaves exstipulate.

Leaf anatomy. Minor leaf veins without phloem transfer cells (Darlingtonia, Sarracenia).

Stem anatomy. Primary vascular tissue centrifugal. Secondary thickening absent. Xylem with tracheids; with vessels. Vessel end-walls oblique; scalariform.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers solitary (mostly), or aggregated in ‘inflorescences’ (Heliamphora); when grouped, in racemes. Inflorescences mostly scapiflorous, or not scapiflorous; terminal, or axillary. Flowers bracteolate (with three bracteoles); medium-sized to large (nodding); regular; cyclic, or partially acyclic (often ‘spirocyclic’). The androecium acyclic. Free hypanthium absent.

Perianth with distinct calyx and corolla, or sepaline (the petals sometimes missing, but then the calyx often coloured and more or less petaloid); (3–)5(–6), or (6–)10(–12); 1 whorled, or 2 whorled; isomerous; sepaloid and petaloid, or petaloid. Calyx (3–)5(–6) (sometimes somewhat petaloid); 1 whorled; polysepalous; regular; persistent; imbricate. Corolla when present, 5; 1 whorled; polypetalous; imbricate; regular; deciduous.

Androecium (10–)50–100 (usually ‘many’). Androecial members branched (in Sarracenia, with several stamens from each of a limited number of primordia — commonly ten), or unbranched; (in Sarracenia) maturing centrifugally; free of the perianth; free of one another, or coherent (in groups, in Sarracenia); in Sarracenia, often 10 adelphous. Androecium exclusively of fertile stamens. Stamens (10–)50–100 (usually ‘many’); isomerous with the perianth to polystemonous. Anthers dorsifixed (Sarracenia), or basifixed; versatile (Sarracenia), or non-versatile; dehiscing via longitudinal slits; introrse; tetrasporangiate. Anther epidermis persistent. Microsporogenesis simultaneous. The initial microspore tetrads tetrahedral. Anther wall initially with one middle layer, or initially with more than one middle layer (1 to 3). Tapetum glandular. Pollen shed as single grains. Pollen grains aperturate; (3–)5–9 aperturate; colporate (colporoidate); 2-celled.

Gynoecium 3 carpelled (Heliamphora), or 5 carpelled. Carpels reduced in number relative to the perianth, or isomerous with the perianth. The pistil 3 celled, or 5 celled. Gynoecium syncarpous; synovarious to synstylovarious; superior. Ovary 3 locular, or 5 locular; sessile. Gynoecium stylate. Styles 1 (subentire in Heliamphora, with 5 short branches each with a terminal stigma in Darlingtonia, or spectacularly expanded-peltate or umbrella-like with a small stigma under the tip of each of the five lobes, in Sarracenia); apical. Stigmas 3, or 5; dry type; papillate; Group II type (b(i)). Placentation axile (at least below, but often intruded-parietal above where the partitions sometimes fail to meet). Ovules differentiated; 50–100 per locule (‘many’); more or less horizontal; anatropous; unitegmic; tenuinucellate. 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; ephemeral to persistent. Synergids pear-shaped. Endosperm formation cellular. Embryogeny caryophyllad.

Fruit non-fleshy; dehiscent; a capsule. Capsules loculicidal. Fruit 50–100 seeded (i.e. ‘many’). Seeds endospermic. Endosperm oily. Seeds small; winged (often, with a winglike beak), or wingless. Embryo well differentiated (but minute). Cotyledons 2. Embryo straight.

Seedling. Germination phanerocotylar.

Physiology, biochemistry. Not cyanogenic. Alkaloids present, or absent. Iridoids detected (?); ‘Route I’ type (+seco). Verbascosides not detected. Proanthocyanidins present; cyanidin. Flavonols present; kaempferol and quercetin. Ellagic acid absent. Saponins/sapogenins absent. Aluminium accumulation not found.

Geography, cytology. Holarctic and Neotropical. Temperate to tropical. Atlantic and Pacific U.S.A., Northern Brazil. X = 13, 15, 21.

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

Species 17. Genera 3; Darlingtonia, Heliamphora, Sarracenia.

Illustrations.
• Technical details: (Sarracenia, Darlingtonia (~Sarracenia).