Trilliaceae Lindl.
Alternatively Parideae (Paridaceae) Dum.
~ Liliaceae
Including Phlebaceae Dulac (p.p.)
Excluding Scoliopus, Medeola (transferred to Uvulariaceae)
Habit and leaf form. Herbs. Autotrophic. Perennial; with neither basal nor terminal aggregations of leaves; rhizomatous, or rhizomatous and tuberous. Mesophytic (mostly woodland species). Leaves whorled (in a single whorl, borne high on the stem); 3(–22) per whorl (generally the same number as the perianth whorls); flat; petiolate to sessile; simple. Lamina entire; lanceolate, or oblong to ovate, or obovate; palmately veined to parallel-veined; cross-venulate; cordate, or attenuate at the base, or cuneate at the base, or rounded at the base. Lamina margins entire; flat.
Leaf anatomy. Lamina dorsiventral. The mesophyll containing calcium oxalate crystals. The mesophyll crystals raphides. Minor leaf veins without phloem transfer cells (Trillium). Vessels absent.
Stem anatomy. Primary vascular tissue in two or more rings of bundles (often 3). Secondary thickening absent. Xylem without vessels.
Root anatomy. Root xylem with vessels. Vessel end-walls scalariform.
Reproductive type, pollination. Fertile flowers hermaphrodite. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the perianth, or from the gynoecium, or from the perianth and from the gynoecium. Entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary (sessile or pedicellate); terminal (on the erect stem); medium-sized (to ‘rather large’); regular; 3–5(–8) merous; cyclic; tetracyclic, or pentacyclic, or polycyclic. Perigone tube absent. Hypogynous disk absent.
Perianth with distinct calyx and corolla, or sepaline, or of ‘tepals’; 6–18; free; 1 whorled, or 2 whorled (the inner whorl sometimes rudimentary or missing, e.g. Paris tetraphylla, Kinugasa); usually isomerous; petaloid, or sepaloid and petaloid; without spots, or spotted; similar in the two whorls to different in the two whorls (often different in shape and/or colour); green, or yellow, or white, or purple; persistent. Calyx (when regarded as such) 3–5(–10); 1 whorled; polysepalous; regular; persistent; imbricate, or contorted. Corolla (when the inner whorl thus interpreted) 3–5(–8); 1 whorled; polypetalous; imbricate, or contorted; regular; green, or white, or yellow, or pink, or purple (etc.); persistent. Petals clawed (sometimes), or sessile; entire.
Androecium 6–10(–24). Androecial members free of the perianth; all equal; free of one another; 2(–6) whorled. Androecium exclusively of fertile stamens. Stamens 6–10(–24); diplostemonous (usually), or triplostemonous, or polystemonous; oppositiperianthial (often portraid thus in floral diagrams), or alterniperianthial. Filaments appendiculate (by prologation of the connective), or not appendiculate. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; extrorse, or latrorse, or introrse; tetrasporangiate. Microsporogenesis successive. Pollen shed as single grains. Pollen grains aperturate, or nonaperturate (Trillium); when aperturate, 1 aperturate; sulcate; 2-celled.
Gynoecium 3–6(–10) carpelled. Carpels isomerous with the perianth. The pistil 1 celled, or 3–6(–10) celled. Gynoecium syncarpous; semicarpous to synovarious, or synovarious to synstylovarious; superior. Ovary 1 locular, or 3–6(–10) locular. Gynoecium in Paris transverse. Ovary sessile. Gynoecium stylate. Styles 1, or 3–6(–10); free, or partially joined; apical. Stigmas dry type; papillate; Group II type (B(i)). Placentation when unilocular, parietal (the placentas strongly intrusive); when plurilocular, axile. Ovules in the single cavity 20–100 (‘many’); 15–50 per locule (‘many’); arillate (usually), or non-arillate; anatropous; bitegmic; crassinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Allium-type. Polar nuclei fusing only after one has been fertilized, or fusing simultaneously with the male gamete (?). Antipodal cells formed; 3; not proliferating; ephemeral, or persistent. Synergids pear-shaped. Endosperm formation helobial (Trillium), or nuclear.
Fruit fleshy to non-fleshy; dehiscent, or indehiscent (when baccate); a capsule (fleshy, e.g. Trillium), or a berry (e.g. Paris). Capsules when dehiscent, splitting irregularly, or septicidal, or loculicidal, or septicidal and loculicidal. Seeds copiously endospermic. Embryo rudimentary at the time of seed release to weakly differentiated. Embryo achlorophyllous (1/1); globose to ovoid. Testa without phytomelan.
Seedling. Hypocotyl internode present (developing into a small tuber). Seedling collar not conspicuous. Cotyledon hyperphyll elongated; assimilatory; dorsiventrally flattened. Coleoptile absent. First leaf dorsiventral. Primary root ephemeral.
Physiology, biochemistry. Not cyanogenic. Proanthocyanidins absent. Flavonols present; kaempferol and quercetin. Ellagic acid absent. Saponins/sapogenins present (steroidal, sometimes poisonous).
Geography, cytology. Holarctic and Paleotropical. Temperate. Temperate Eurasia, North America. 2n = 10, 15, 20, 30, 40. Supposed basic chromosome number of family 5. Ploidy levels recorded 2, 3, 4, 6, and 8.
Taxonomy. Subclass Monocotyledonae. Superorder Liliiflorae; Dioscoreales. Species 53. Genera 4; Daiswa, Kinugasa, Paris, Trillium.
Discussed in detail by Zomlefer (1996).
Illustrations. • Trillium sessile. • Paris quadrifolia. • Technical details (Paris, Trillium).
Quotations
Small good to anything growing wild,
They were
crooking many a trillium
That had budded before the boughs were piled
(Robert Frost, ‘Pea Brush’)
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).
