Crassulaceae

Crassulaceae, the crassulaceae, form a large family of plants in the order Saxifragales. They are generally herbaceous plants, some subshrubs and relatively few arboreal or aquatic. They are widespread worldwide, but mostly in the northern hemisphere and southern Africa. These plants store water in their succulent leaves, since their habitat is typically dry and hot areas, where water is scarce. There are about 1,400 accepted species in 35 genera.

Features

Simple leaves of various arrangement, alternate, opposite or in a basal rosette, without stipules. Hermaphrodite flowers, regular; dichlamyd perianth, often pentameric, sometimes tetrameric, hexamerous and rarely multimeric, calyx sometimes more or less welded at the base; isostemonous or diplostemonous androecium, welded to the corolla tube; gynoecium superior with several free or welded carpels at the base. Inflorescences often cymose. Capsular or follicular fruits.

They have a particular metabolism, which is why they are sometimes called CAM plants, which consists in the fact that photosynthesis takes place in two separate phases, a phototrophic (light) phase during the day and a synthetic (dark) phase at night. The name CAM photosynthesis (crassulacean acid metabolism) was given after first discovering this type of photosynthesis in crassulaceae.

Cultivation

Many of the species in this family are popular in gardening and floriculture; They are hardy plants, many of them strange looking and require minimal care. Another advantage for the cultivation of these plants is how easy it is to propagate, in some cases requiring a single leaf to produce a new specimen.

Classification is difficult due to its ease of hybridization, both wild and cultivated. Formerly they were included in the order of the rose bushes, but at present they have been classified in the order Saxifragales.

Taxonomy

The family was created by Jean Henri Jaume Saint-Hilaire and published in Exposition des familles naturelles et de la germination des plantes, containing the description of 2,337 genres et d'environ 4,000 species, 112 plates dont les figures ont été dessinées par l'auteur. Paris, in 1805.

Etymology

Crassulaceae, from Latin crassus,-a, -um, meaning "thick, greasy, dense" because of the leaves that are thick.

Subdivisions

There are many discrepancies, insurmountable it seems, about the delimitation of families, tribes and genera:

Classically it has the following subfamilies: Crassuloideae - Cotyledonoideae - Echeverioideae - Kalanchoideae - Sedoideae - Sempervivoideae.

On the other hand, the Angiosperm Phylogeny Website, followed by others, limits the number of subfamilies to 3, the number of genera to 34, and the number of species to 1,400:

• Crassuloideae Burnettwith 2 gendersCrassula and Tillaea) and 196 species;
• Kalanchoideae A.Bergerwith 4 gendersKalanchoe and Tylecodon as more important) and 200 species;
• Sempervivoideae Arnottwith 28 gendersSedum, Echeveria, Rhodiola, Sempervivum and Dudleya as more important) and 1005 species.

While recently (1995 and 2012), a division without subfamilies, but with tribes and subtribes, was proposed:

• tribe Aeonieae Thiede ex Reveal Phytoneuron 2012-37: 215, 2012
• tribe Kalanchoeae 't Hart in H. 't Hart & U.Eggli (eds.), Evol. & Syst. Crassulac, 167, 1995
• tribe Headquartersae 't Hart in H. 't Hart & U. Eggli (eds.), Evol. & Syst. Crassulac, 167, 1995
  • sub- Sedinae 't Hart in H. 't Hart & U. Eggli (eds.), Evol. & Syst. Crassulac, 169, 1995
  • sub- Telephinae 't Hart in H. 't Hart & U. Eggli (eds.), Evol. & Syst. Crassulac, 167, 1995

Genres

• Adromischus Lem. - 28 spp.
• Aeonium Webb & Berth. - 75 spp.

Aeonium arboreum (L.) Webb & Berth.

• Aichryson Webb & Berth. - 17 spp.
• Cotyledon Tourn. ex L. - 12 spp.
• Crassula L. 207 spp.

Crassula tillaea Lest.-Garl., tiny size; Crassula vaillantii (Willd.); Crassula campestris (Eckl. & Zeyh.) Endl. ex Walp.in Catalonia and Ciudad Real.

• Dudleya Britton & Rose - 46 ssp
• Echeveria DC. - 167 spp.
• Graptopetalum Rose - 18 spp.
• Greenovia Webb & Berth. - 3 sp.

• Hypagophytum A.Berger - 1 sp.
• Kalanchoe Adans - 73 spp.
• Lenophyllum Rose - 7 spp.
• Monanthes Haw. - 10 spp.
• Mucizonia A.Berger

Mucizonia hispida (Lam.) A.Berger, Mucizonia sedoides (DC.) D.A.Webb

• Orostachys Fisch. - 12 spp.
• Pachyphytum Link, Klotzsch & Otto - 17 spp.
• Perrierosedum (A.Berger) H.Ohba - 1 sp.
• Phedimus Raf. - 4 spp.
• Pistorinia DC. - 2 spp.

Pistorinia hispanica (L.) DC.

• Prometheum (A.Berger) H.Ohba - 8 sp.
• Pseudosedum A.Berger - 4 spp.
• Rhodiola L. - 61 spp.

Rhodiola rosea L.

• Rosularia Stapf - 25 spp.
• Sedum L. - 348 spp.

Sedum acre L.; Sedum aizoon L.; Sedum album L.; Sedum alpestre Vill., Sedum andagavense (DC.) Desv....

• Sempervivum L. - 30 spp.

Sempervivum tectorum L.always live longer; Alwaysvivum arachnoideum L., Alwaysvivum montanum L.

(Salisb.) Dandy

• Thompsonella Britton & Rose - 6 spp. - (Mexico)
• Tylecodon Toelken - 2 spp.
• Umbilicus DC. - 9 spp.

Umbilicus heylandianus Webb & Berth.; Umbilicus horizontalis DC.; Umbilicus rupestris

• Villadia Rose - 43 spp.

• Other less important genders:

Note 1: The species listed below from certain genera are examples of the most common of them.

Note 2: The number of species in each genus is the number of accepted species, not those described.