Crassuloideae

Subfamily I is set apart from the remainder by the single whorl of stamens, equal in number to the sepals, petals and carpels. It is not a primitive character, because it results from suppression of a second whorl, and a reduced pollen output is characteristic of more specialized flowers that can afford to be less wasteful of pollen. A phylogenetic classification of

the Crassulaceae, according to Uhl. would look to Sedum as a more likely starting

P The 250 to 300 species of Crassula run from tiny, cosmopolitan annuals ignored by collectors to the tallest members of the Family, and cover the broadest ecological tolerance of any genus of flowering plants, from the deserts of South West Africa, where the leaf rosette is condensed to a sphere giving minimal surface for evaporation, to marshy and even aquatic habitats. South Africa is the centre of greatest diversity, with outliers extending far and wide. Nearly all perennial species have collector appeal, and the genus as a whole can be recommended to anyone in search of a group of succulents ideal for specializing upon, and not already wedded to the more popular genera of cacti. Xeromorphic features are much in evidence and provide the principal attraction, as in the white glaucous "bloom" of C. cornuta and deltoidea. the hairs of C. barbata, lanuginosa and tomentosa, the incrustations of papillae in C. falcata. hystrix and tecla, and the packing of leaves into columns, square in C. aria (10.5), barklyi and pyramidalis, almost spherical in C. columnaris (2.7) and hemispherica (10.4).

Crassula falcata and C. (Rochea) coccinea are raised as florists' flowers and widely valued as pot plants for their long-lasting showy heads of crimson blooms. Crassula sarcocaulis (6.12) and C. milfordiae are sufficiently hardy to overwinter in the open in frosty areas. A useful introductory book is Crassulas in

Cultivation by Vera Higgins, 1964.

The other genera of Crassuloideae, Dinacria and Vauanthes (page 118), are short-lived annuals and rarely cultivated.

Kalanchoideae

In contrast to the hardy members of other subfamilies, the large genus Kalanchoe (130 species approximately) comes mainly from Madagascar and tropical Africa and appreciates more warmth in cultivation—a winter minimum of at least 10°C (50°F) for best results, and a correspondingly richer soil and ample watering. The subfamily is sharply distinguished from all others by the flower parts in fours, but species of Cotyledon run very close and can be separated only by this feature, so they are, I suspect, blood relatives. Most kalanchoes are rather large-growing and hence shunned by collectors, although, given space, the flowers can put up quite a show. The smaller species, such as K. pumila (page 118) and K. manginii, are justly popular and make good basket plants. The former has grey leaves with a waxy bloom that act as a foil to the beautiful mauve flowers; the latter has vivid red tubular blooms against soft green foliage. K. marmorata has agreeably dappled leaves, and K. tomentosa (10.7). which has an overall covering of white felt with dark tips to the leaves, is called the "Panda Plant' and rarely blooms. A delightful miniature is K. rhombopilosa, similar in habit to Adromischus, but less robust. K. tubiflora, with cylindrical leaves, and K. daigremontiana (6.23), with triangular ones—both sometimes classified as a separate genus, Bryophyllum—a re among the most ubiquitous of succulents from

Right (10.6]: Kalanchoe thyrsitlora in habitat on a wooded slope in Makowe Natal Flowering stems go up to 60cm (210 in height.

Below (10.7): Downy and lurry-leaved succulents are lorever popular. Compare this Kalanchoe tomentosa from Madagascar with the Mexican Echeveria leucotricha (10.10}.

the ease with which they drop adventitious buds from the leaf margins and spawn large numbers of offspring.

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