[FAMILY 94.] HYDROSTACHYACEAE
Aquatic herbs. Stem tuberous. Leaves with a sheath and a ligule. Flowers in spikes, bracteate, without a perianth, dioecious. Stamen 1, with separated anther-halves (or 2 with united filaments), hypogynous. Anthers turned outwards. Pollen-grains united in groups of 4. Ovary 1-celled, with 2 parietal placentas. Ovules numerous, inverted. Styles 2. Fruit capsular. Seeds exalbuminous. (Under PODOSTEMONACEAE.) (Plate 58.)
Genus 1, species 15. Tropical and South-east Africa. Hydrostachys Thouars
SUBORDER SAXIFRAGINEAE
[FAMILY 95.] CRASSULACEAE
Herbs or undershrubs, rarely shrubs. Stem and leaves usually succulent. Leaves without stipules. Flowers regular, hermaphrodite. Petals 3-20, free or united below, hypogynous or nearly so. Stamens as many or twice as many as the petals. Filaments free. Anthers turned inwards. Carpels as many as the petals, free or united at the base, usually with a scale-like appendage. Ovules numerous, rarely (Crassula) 1-2 in each carpel. Fruit-carpels follicular. Seeds with a very scanty albumen or without albumen.—Genera 10, species 400. (Plate 59.)
1. Petals free or nearly so. 2
Petals united below into a distinct, usually long tube. 5
2. Stamens as many as the sepals or petals, 3-9, usually 5. Sepals free or nearly so. Petals white or reddish. Leaves opposite.—Species 180.
Some of them are used as ornamental or medicinal plants. (Including
Bulliarda DC., Dinacria Harv., Helophytum Eckl. & Zeyh., and Tillaea
L.) Crassula L.
Stamens twice as many as the sepals, rarely (Sedum) equalling the sepals in number, but then leaves alternate. 3
3. Flowers 4-5-merous, very rarely 6-7-merous. Sepals free or nearly so. Leaves usually scattered.—Species 25. North Africa and high mountains of East Africa. Some species are used as vegetables or as medicinal or ornamental plants. Sedum L.
Flowers 6-20-merous, very rarely 5-merous. Sepals more or less united.
Leaves usually rosulate. 4
4. Scale-like appendages of the carpels broad, petaloid. Petals linear-lanceolate, inconspicuous, reddish or yellowish.—Species 10. North-west
Africa. (Petrophyes Webb). Monanthes Haw.
Scale-like appendages of the carpels small or wanting. Petals lanceolate, brightly coloured.—Species 70. North Africa and northern Central
Africa. Some are used as ornamental or medicinal plants. “House-leek.”
(Including Aeonium Webb, Aichryson Webb, and Greenovia
Webb & Berth.) Sempervivum L.
5. Flowers 4-merous. Leaves opposite. 6
Flowers 5-6-merous. 8
CRASSULACEAE.
FLOW. PL. AFR.