Sium

No map specified
Authors: L.
Protologue: Sp. Pl. ed. 1: 251
Synonyms: Sisarum Mill., Sion Adans., Drepanophyllum Hoffm., Critamus Hoffm., Siumis Raf.
Type species: Sium latifolium
Type species authors: L.
Type species synonyms: No synonyms
Number of species: 14
Distribution: Europe, Asia, Africa (trop., S), N America
Bibl.: No bibliography
No illustration specified

Features: fruits separating into mericarps or fruits free, not separating into mericarps; orbicular or elliptic; with carpophore bifid to the base or with carpophore bifid to the middle or with entire carpophore or carpophore obsolete; beak absent; mericarps homomorphic; glabrous; 2.0-7.0 mm long; 2.0-4.0 mm broad; terete; with primary ribs; all primary ribs equal, filiform or all primary ribs equal, keeled or all primary ribs equal, narrow-winged; mericarp ribs straight; with entire margin; calyx teeth prominent or calyx teeth obsolete; short or equal to stylopodium; triangular; stylopodia low conical or stylopodia conical; styles short or styles medium; recurved; cell borders indistinct; surface longitudinally rugate; cuticle striate with straight striae; exocarp cells small; commissure narrow, exocarp almost reaches carpophore; inner fibrous mesocarp obsolete; mesocarp parenchyma not lignified or mesocarp parenchyma partly composed of cells with lignified pitted walls; vascular bundles compact; vittae vallecular and commissural; solitary in furrows or 2–5 in each furrow; two on commissural side or 4–10 on commissural side; rib sectetory ducts small, present in some ribs only or rib sectetory ducts obsolete; endocarp not lignified; endosperm flat, slightly convex or slightly concave on commissural side; embryo with two cotyledons.

Note: СЭМ: Границы клеток неразличимы, поверхность на ребрах продольно бороздчатая, в ложбинках продольно морщинистая, беспорядочно морщинистая и бугорчато-ямчатая. Кутикула струйчатая.