| # The Families of Angiosperms |

L. Watson and M.J. Dallwitz

### Japonolirionaceae

~ Tofieldiaceae, Petrosaviaceae, Liliaceae ....

Habit and leaf form. Glabrous, green herbs. Perennial; with a basal aggregation of leaves (the radical leaves sometimes exceeding the scape); creeping, shortly rhizomatous. Mesophytic (in alpine meadows). Leaves medium-sized to large (5–15 cm long, 2–4 mm wide); alternate; distichous; flat; pointed, basally narrowing; sheathing; with blades borne edgewise to the stem; simple. Lamina entire; linear; parallel-veined; attenuate to the base. Lamina margins scabrous; flat.

Leaf anatomy. The leaf lamina bifacial (?). Midrib not conspicuous.

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

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes. The ultimate inflorescence units racemose. Inflorescences solitary, scapiflorous; terminal; dense, racemose, simple, erect, several- to many flowered, sometimes exceeded by the basal leaves; espatheate. Flowers bracteate (the bracts similar to the proximal scales of the scape); ebracteolate; minute to small (the perianth 2.5–3 mm long); regular; cyclic; pentacyclic. Perigone tube absent (or slight?). Hypogynous disk absent.

Perianth of ‘tepals’; 6; free (no more than basally contiguous, in Ohwi's illustration); 2 whorled; isomerous; membranous, 1-nerved; without spots; somewhat different in the two whorls (the inner three members larger); white and hyaline; persistent.

Androecium 6. Androecial members free of the perianth, or adnate (adnate to the bases of perianth segments?); more or less all equal; free of one another; 2 whorled. Stamens 6; isomerous with the perianth; oppositiperianthial; filantherous. Anthers basifixed; dehiscing via longitudinal slits; introrse; bilocular.

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; semicarpous to synovarious (with only the carpel apices diverging); superior. Ovary 3 locular; sessile. Gynoecium stylate. Styles 3; free; apical (stigmatic on their inner surfaces); short, recurved shorter than the ovary. Placentation basal to axile (?).

Fruit non-fleshy; dehiscent; a capsule. Capsules septicidal.

Geography, cytology. Holarctic. Temperate, sub-tropical. Confined to serpentine swamps in Honshu and Hokkaido, Japan. Eastern and Southern Asia.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Liliiflorae; Melanthiales. APG III core angiosperms; Superorder Lilianae; non-commelinid Monocot. APG IV Order Petrosaviales.

Species 1. Genera 1; Japonolirion osense.

General remarks. Description encoded from Ohwi, Flora of Japan (1965), cross referenced with Christenhusz et al. (2017); i.e., lacking the reliable comparative data essential for critical taxonomic evaluation.

Illustrations. • Japonolirion osense: Ohwi, Flora of Japan (1965).

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: 8th June 2026. delta-intkey.com’.

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