FRUIT STRUCTURE IN <i>LOZANELLA ENANTIOPHYLLA </i>AND <i>L. PERMOLLIS (CELTIDACEAE)</i>
Morphological and anatomical structure of drupaceous fruit in <i>Lozanella enantiophylla</i> and <i>L. permollis (Celtidaceae / Celtidoideae)</i> was examined using light and scanning electron microscopes. Sclerified inner pericarp (stone / endocarp body) was investigated for the first time using SEM in some other <i>Celtidaceae</i> (which are similar with <i>Lozanella</i> in pericarp anatomy according to V. V. Chernik (1980) — <i>Aphananthe, Gironniera, Parasponia, Trema</i>), and members of the <i>Cannabaceae</i>. It was found that both <i>Lozanella</i> species have similar fruit structure. As in other <i>Celtidaceae</i>, two stigmas and pendulous ovule are typical of them; anatomical structure and micromorphology of endocarp body are similar. Only the embryo of <i>Lozanella</i>, being longitudinally curved, is found to be unique in the <i>Celtidaceae</i>. It resembles the embryo of only one genus of the group — <i>Holoptelea (Ulmaceae)</i> (according to the description by Grudzinskaya, 1967). Every genus of the <i>Celtidaceae</i> has its own distinctive set of endocarp body features (shape, surface, primary sculpture of outer and middle layer of its wall). The greatest endocarp body resemblance is found with <i>Trema</i> and <i>Parasponia</i>, the lesser — with <i>Gironniera</i>, and only remote one — with <i>Aphananthe</i>, who has the larger endocarp body. In all <i>Celtidaceae</i> studied the same three layers are distinguished in the endocarp body wall: over the endocarp of very large sclereids (often macrosclereids) there are two sclerified mesocarp layers; inner one is built of small flat, mostly lobed sclereids with thin outer wall, filled with amorphous silica, and the outer one — of large cells with concave silicified inner wall. Several scattered cells of the exterior layer contain siliceous inclusions and project above neighboring empty cells (except <i>Aphananthe</i> where all cells accumulate these inclusions, and <i>Gironniera</i> where inclusions absent). The results obtained have shown that <i>Celtidaceae</i> are similar with <i>Cannabaceae</i> by anatomical structure and micromorphology of the endocarp body, except its outer layer (outer of two sclerified mesocarp layers) presents only in <i>Humulus scandens</i>; this layer is apparently lost in the endocarp body of two other <i>Cannabaceae</i> species — <i>Humulus lupulus</i> and <i>Cannabis sativa</i>. The reduction of pericarp layers was attended by diminution of siliceous content and (as noted P.I. Dorofeev, 1982) by simplification of endocarp sclereids structure in these recent species in comparison with extinct <i>Humulus species, H. scandens</i> and <i>Celtidaceae</i>. The same structural pattern of sclerified inner pericarp (but less conformable) is observed in some members of the <i>Urticaceae — Gibbsia, Leucosyce, Maoutia</i> (Kravtsova, 2001): surface tubercles are formed by silica, projecting at the centre of lobed sclereids, and not by silica bodies of the superficial layer, as in <i>Celtidaceae</i>, and endocarp sclereids being usually much smaller. The results indicate to close relationships of <i>Celtidaceae</i> and <i>Cannabaceae.</i> At the same time the resemblance in pericarp structure could arise in these groups independently too. Thus, resemblance (lesser) by the characters between <i>Celtidaceae</i> and more remote <i>Urticaceae</i> resulted, most probably, from parallel pericarp development in these families. The similarity observed in the pericarp structure in the <i>Celtidaceae, Cannabaceae</i>, and some <i>Urticaceae</i> supports the proposition (Melikjan, 1973; Kravtsova, 2007) that pericarps in closely related urticalean families are frequently the variants of the same structural type, and differ only in details.