The families of flowering plants

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L. Watson and M. J. Dallwitz

Trilliaceae Lindl.

Alternatively Parideae (Paridaceae) Dum.; ~ former Liliaceae, Melanthiaceae.

Including Phlebaceae Dulac (p.p.); excluding Scoliopus, Medeola (transferred to Uvulariaceae).

Habit and leaf form. Herbs. ‘Normal’ plants. Plants non-succulent; autotrophic. Perennial; without conspicuous 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. The leaf lamina dorsiventral. The mesophyll containing crystals. The crystals raphides. Foliar vessels absent. Minor leaf veins without phloem transfer cells (Trillium).

Axial (stem, wood) anatomy. Primary vascular tissues comprising two or more rings of bundles (often 3). Secondary thickening absent. The axial xylem without vessels.

Root anatomy. Root xylem with vessels; vessel end-walls scalariform.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the perianth, or from the gynoecium, or from the perianth and from the gynoecium. Pollination 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, phytochemistry. Not cyanogenic. Saponins/sapogenins present (steroidal, sometimes poisonous). Proanthocyanidins absent. Flavonols present; kaempferol and quercetin. Ellagic acid absent.

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. Dahlgren et al. Superorder Liliiflorae; Dioscoreales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Liliales (as a synonym of Melanthiaceae).

Species 53. Genera 4; Daiswa, Kinugasa, Paris, Trillium.

General remarks. Discussed in detail by Zomlefer (1996). The attempted comparative descriptions compiled for the present package have Trilliaceae differing conspicously from Melanthiaceae (q.v.) in the whorled leaves and solitary flowers, also the seeds with weakly differentiated embryo and (in so far as sampling has been adequate) differences in embyrology.

Illustrations. • Paris polyphylla: Hooker’s Illustrations of Himalayan plants (1855). • Paris quadrifolia (B. Ent.). • Technical details: Paris, Trillium. • Trillium sessile: Bot. Mag. 2, 1788.

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’)


This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using 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).

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 August 2014. http://delta-intkey.com’.

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