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The families of flowering plants.                                                                                                                                                                

Apostasiaceae Bl.

                       

 

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~Orchidaceae

IncludingNeuwiediaceae (Burns-Balogh & Funk) R. Dahlgren ex Reveal & Hoogland

Habit and leaf form. Leaves simple. Lamina entire; lanceolate; parallel-veined; without cross-venules. Vernation plicate.

General anatomy. Plants with silica bodies (these in idioblasts (stegmata) occurring along the fibres surrounding the vascular bundles).

Leaf anatomy. Epidermis without silica bodies. Stomata present; tetracytic, or anomocytic and tetracytic. Hairs absent.

The mesophyll containing calcium oxalate crystals. The mesophyll crystals raphides. Vessels absent.

Stem anatomy. Primary vascular tissue in scattered bundles; centrifugal. Secondary thickening absent. Xylem without vessels.

Root anatomy. Roots with velamen. Root xylem with vessels; vessel end-walls scalariform and simple (mainly simple).

Reproductive type, pollination. Plants hermaphrodite.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’. The ultimate inflorescence unit racemose. Inflorescences scapiflorous; racemes, sometimes branched; espatheate. Flowers somewhat irregular to very irregular; more or less zygomorphic; resupinate (Neuwiedia), or not resupinate (Apostasia). The floral irregularity involving the perianth and involving the androecium (more consistently the latter). Flowers 3 merous; cyclic; supposedly basically pentacyclic. Perigone tube absent.

Perianthof ‘tepals’; 6 (3+3); free; 2 whorled (the median inner member sometimes larger, forming a labellum); isomerous; petaloid; white, or yellow.

Androecium 2–3 (the median of the outer whorl, which is sometimes missing, and the two laterals of the inner whorl). Androecial members free of the perianth; partially united with the gynoecium; coherent (at the base, and with the style); theoretically 2 whorled, or 1 whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes when present, 1 (the median member); external to the fertile stamens. Stamens 2, or 3; isomerous with the perianth; alterniperianthial (when the median of the outer whorl is present), or oppositiperianthial (when only the two laterals of the inner whorl are present); filantherous to with sessile anthers. Anthers dorsifixed to basifixed; dehiscing via longitudinal slits; introrse. The endothecial thickenings spiral. Microsporogenesis simultaneous. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; sulcate (operculate).

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled.Gynoecium syncarpous; eu-syncarpous; inferior. Ovary 3 locular. The ‘odd’ carpel anterior. Styles 1. Stigmas 1; 2–3 lobed; capitate. Placentation axile. Ovules 10–50 per locule (i.e. ‘many’); anatropous.

Fruit fleshy, or non-fleshy; indehiscent (disintegrating, usually), or dehiscent; a capsule. Capsules when dehiscent, loculicidal (Neuwiedia). Fruit 30–100 seeded (‘many’). Seeds minute. Embryo rudimentary at the time of seed release, or weakly differentiated. Testa without phytomelan; hyaline.

Seedling.Seedling collar not conspicuous. Coleoptile absent. Primary root ephemeral.

Geography, cytology. Tropical. S.E. Asia, Indomalaya, tropical Australia.

Taxonomy.Subclass Monocotyledonae. Dahlgren et al. Superorder Liliiflorae; Orchidales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Asparagales (as a synonym of Orchidaceae).

Species 20. Genera 3; Apostasia, Adactylus, Neuwiedia.

 Illustrations:

  • Technical details (Lindley).   
  • Floral diagrams (Apostasia, Neuwiedia).
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