Ceratophyllaceae Gray

Ceratophyllaceae, C.M. Wilmot-Dear. Flora of Tropical East Africa. 1985

Morphology General Habit

Aquatic herbs, monoecious, perennating by buds, usually free-floating

Morphology Leaves

Leaves in whorls of (6–)8–11, filiform, dichotomously branched, often with few–many spine-tipped teeth on margins especially of distal segments; terminal segments truncate, 2-spined and with a central reddish terete soon deciduous projection ± 0.2 mm. long

Morphology Reproductive morphology Flowers

Flowers axillary, 1-several per node, ? and ? at different nodes Female flowers sessile or shortly pedicellate, without staminodes; ovary solitary, superior, sessile, tapering into long style; ovule 1, pendulous Male flowers subsessile, with numerous stamens in several whorls on domed torus around pistillode; filaments very short or absent; anthers oblong, extrorse; thecae 2, parallel, dehiscing longitudinally; connective produced apically into 2 spines and a central projection as in perianth-lobes, often with 1–3 spines on margins; immature anthers much flattened, resembling perianth-lobes, later swollen, oblong, reddish projection detaching, tissues becoming gas-filled and bearing detached anther to water-surface where it becomes horizontal, dehisces and sheds pollen on to plants below

Morphology Reproductive morphology Flowers Perianth

Perianth of 6–13 strap-shaped or obovate lobes united at base and some united in pairs to over half their length, often with a single hyaline spine on each margin, truncate with 2 spines and a central projection as in leaves

sex Male

Male flowers subsessile, with numerous stamens in several whorls on domed torus around pistillode; filaments very short or absent; anthers oblong, extrorse; thecae 2, parallel, dehiscing longitudinally; connective produced apically into 2 spines and a central projection as in perianth-lobes, often with 1–3 spines on margins; immature anthers much flattened, resembling perianth-lobes, later swollen, oblong, reddish projection detaching, tissues becoming gas-filled and bearing detached anther to water-surface where it becomes horizontal, dehisces and sheds pollen on to plants below

sex Female

Female flowers sessile or shortly pedicellate, without staminodes; ovary solitary, superior, sessile, tapering into long style; ovule 1, pendulous

Morphology Reproductive morphology Fruits

Fruit a hard nut, ovoid or ellipsoid, slightly laterally flattened, wingless and rimless, or more markedly flattened and then often with marginal longitudinal ‘rim’ or entire to dentate or spinulose wing; style ± persistent and spinose; base often with a pair of prominent spines; rest of surface often gland-dotted, spiny or warty; embryo straight; endosperm absent

Distribution

A worldwide family of one genus only

Ceratophyllaceae, C. M. Wilmot-Dear. Flora Zambesiaca 9:6. 1991

Morphology General Habit

Submerged aquatic, branching, usually rootless herbs, perennating by buds, monoecious

Morphology Leaves

Leaves in whorls, filiform, once or more dichotomously branched, margins ± spinose-dentate; apical segments truncate, 2-spined at the apex with a reddish glandular projection between the spines (basal segments sometimes parasitised, becoming swollen and sac-like)

Morphology Reproductive morphology Flowers

Flowers axillary, 1-several per node, male and female flowers at different nodes, ± sessile; perianth lobes 6–13, united at the base, strap-shaped or obovate, margin often with a single lateral hyaline spine or ± lacerate, apex as for leaf apex Female flowers sessile or shortly pedicellate; staminodes absent; ovary superior, sessile, ovoid, tapering into a long style; ovule 1, pendulous Male flowers subsessile; stamens up to c. 30 in several whorls on a domed torus around the pistillode; filaments short or absent; anthers oblong, extrorse, 2-locular, dehiscing longitudinally, connective produced apically into 2 spines and a central projection as in perianth lobes, immature anthers resembling perianth lobes, margins 1–3 spined; mature anthers detach and float to the water-surface where they dehisce and shed pollen on to plants below

sex Male

Male flowers subsessile; stamens up to c. 30 in several whorls on a domed torus around the pistillode; filaments short or absent; anthers oblong, extrorse, 2-locular, dehiscing longitudinally, connective produced apically into 2 spines and a central projection as in perianth lobes, immature anthers resembling perianth lobes, margins 1–3 spined; mature anthers detach and float to the water-surface where they dehisce and shed pollen on to plants below

sex Female

Female flowers sessile or shortly pedicellate; staminodes absent; ovary superior, sessile, ovoid, tapering into a long style; ovule 1, pendulous

Morphology Reproductive morphology Fruits

Fruit a nut, ovoid or ellipsoid, often warty and basally-spined, style ± persistent, spinose

Morphology Reproductive morphology Seeds

Embryo straight, endosperm absent

Milliken, W., Klitgard, B. and Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://creativecommons.org/licenses/by/3.0

Morphology General Habit

Submersed aquatic, rootless, glabrous herbs

Morphology Leaves

Leaves whorled simple, finely divided (often dichotomously branched), lobes often toothed, petiole inconspicuous or lacking

Morphology Reproductive morphology Inflorescences

Inflorescences extra- axillary and alternating with leaves, spikes or racemes

Morphology Reproductive morphology Flowers

Flowers solitary, unisexual, monoecious, actinomorphic, pedicels short or flowers sessile, bracts foliaceous; calyx of (7)9-12(15) toothed sepals; corolla lacking; stamens 3-many, spirally arranged, free of perianth, filaments short, anthers adnately fixed, dehiscing via full-length slits; ovary superior, monomerous, style 1, persistent, spiny, occasionally bifid

Morphology Reproductive morphology Fruits

Fruits achenes, papillose, spiny or smooth

Morphology Reproductive morphology Seeds

Seeds 1, tiny.

Distribution

Throughout the Neotropics in non-marine aquatic habitats.

Diagnostic

Key differences from similar families: Distinguished from Myriophyllum L. (Haloragaceae) by the branched leaves and achenefruit. Distinguishing characters (always present): Aquatic herbs. Leaves in whorls of 3-10. Roots lacking. Stamens ca. 3-45. Styles persistent on fruits. Native and naturalizing; has become a problem weed harbouring vectors of diseases threatening human health and choking the waterways in which they inhabit.

Note

Number of genera: One genus Ceratophyllum L. with three of the six cosmopolitan species: C. demersum L., C. submersum L. and C. muricatum (Cham.) occurring in the Neotropics. General notes: Notes on delimitation: Recently placed in an order of its own - the Ceratopyllales with molecular evidence positioning Ceratophyllaceae as probable sister to eudicots (APG III, 2009). The development and complicated make-up of the perianth has led the family to be compared with the ANITA clade (excluding Nymphales).