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Alternatively Myzodendraceae auctt.
Habit and leaf form. Chlorophyllous (under-) shrubs (or rather, shrublets). More or less ‘normal’ plants, or switch-plants. Leaves well developed (but small), or much reduced. Plants rootless (in the normal sense); parasitic; haustorially parasitic; pale green and photosynthesizing; parasitic on aerial parts of the host (of Nothofagus, the thickened haustoria promoting overgrowth of the host at the contact zone). Stem growth conspicuously sympodial (the apices of the stout twigs aborting at the end of each season). Leaves small; alternate; ‘herbaceous’, or leathery, or membranous; simple. Lamina entire. Leaves exstipulate.
Leaf anatomy. The leaf lamina homogeneous, with the mesophyll of isodiametric cells. Stomata on both surfaces (lying parallel to the midrib). Hairs present; eglandular; unicellular. Unicellular hairs simple. Complex hairs absent. Main veins embedded (veins not accompanied by sclerenchyma).
Axial (stem, wood) anatomy. Primary vascular tissues in a cylinder, without separate bundles (Section Gymnophyton), or comprising a ring of bundles (Section Eumyzodendron); collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring, or anomalous (subgenus Eumyzodendron). The anomalous secondary thickening when present, via concentric cambia (generating a secondary ring of bundles internally: see illustration). Primary medullary rays narrow (uniseriate, in Gymnophyton), or wide (in Eumyzodendron).
The vessel end-walls simple. The axial xylem with fibre tracheids; without libriform fibres. ‘Included’ phloem absent. The wood storied, or partially storied (VPI).
Reproductive type, pollination. Unisexual flowers present. Plants dioecious. Female flowers with staminodes (three, situated in longitudinal furrows of the ovary and lengthening to form long, plumose bristles on the fruit). Gynoecium of male flowers absent.
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, or in spikes, or in catkins. Inflorescences catkinlike, compound racemes or spikes. Flowers bracteolate, or ebracteolate; very small, or minute.
Perianth sepaline, or vestigial (present, but much reduced, in female flowers), or absent (from male flowers); of female flowers, 3; 1 whorled. Calyx of female flowers 3; 1 whorled; gamosepalous (at the base); blunt-lobed (the three members adnate to the ovary except along their margins, but separate from each other save at the very base, and projecting beyond the ovary as three short, free lobes); open in bud.
Androecium of male flowers, 2–3. Androecial members free of one another (seated around a small, lobed nectary). Androecium exclusively of fertile stamens. Stamens 2–3. Anthers basifixed (terminal); dehiscing via short slits (the slit terminal, tangential); unilocular; bisporangiate. Pollen shed as single grains. Pollen grains aperturate; 4–12 aperturate; foraminate.
Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 1 celled. Gynoecium syncarpous; synstylovarious; partly inferior (by virtue of the adnate calyx). Ovary 1 locular. Epigynous disk present (annular). Gynoecium very shortly stylate. Styles 1; apical; shorter than the ovary. Stigmas 3. Placentation free central. Ovules not differentiated; in the single cavity 3; pendulous (from the top of the placental column); curved; without integuments; tenuinucellate. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Synergids pear-shaped. Endosperm formation cellular. Endosperm haustoria present; chalazal. Embryogeny complex and unusual, cf. some Olacaceae.
Fruit non-fleshy; indehiscent; three-angled or -winged, achene-like, or a nut (crowned by the accrescent, feathery, pappus-like staminodes). Dispersal by wind. Fruit 1 seeded. Seeds endospermic. Endosperm oily. Seeds without a testa. Embryo chlorophyllous (1/1); straight.
Seedling. Germination phanerocotylar.
Geography, cytology. Neotropical and Antarctic. Temperate. Southwest temperate South America.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Santaliflorae; Santalales. Cronquist’s Subclass Rosidae; Santalales. APG III core angiosperms; core eudicot; Superorder Santalanae. APG IV Order Santalales.
Species 8. Genera 1; only genus, Mizodendrum.
Illustrations. • Misodendrum punctulatum, on Nothofagus: Hooker, Fl. Antarctica (1844). • Misodendrum punctulatum and M. brachystachyum, on Nothofagus: Hooker, Fl. Antarctica (1844). • Misodendrum punctulatum and M. brachystachyum, on Nothofagus: Hooker, Fl. Antarctica (1844). • Anatomical details of Misodendrum brachystachyum, M. linearifolium, M. punctulatum and M. quadriflorum: Hooker, Fl. Antarctica (1844). • Le Maout and Decaisne: Misodendrum. • TS stems of Misodendrum oblongifolium, detailing anomalous secondary thickening (Solereder, 1908).
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: 4th May 2024. delta-intkey.com’.
