The Families of Flowering Plants
L. Watson and M. J. Dallwitz
Crassulaceae DC.
Including
Isocarpellaceae Dulac,
Sempervivaceae Juss.
Habit and leaf form. Herbs, or
shrubs (or ‘treelets’).
Plants succulent. Perennial; with a
basal aggregation of leaves, or with neither
basal nor
terminal aggregations of leaves.
Xerophytic (mostly), or
mesophytic, or
hydrophytic (rarely).
Leaves evergreen;
alternate, or
opposite, or
whorled; when alternate,
spiral; flat (more or less), or
terete;
fleshy;
petiolate to
subsessile; non-sheathing;
not gland-dotted; simple;
peltate (sometimes), or not
peltate.
Lamina entire (usually), or
dissected (e.g. sometimes in
Bryophyllum, Kalanchoe); when dissected,
pinnatifid; one-
veined, or
pinnately veined; cross-venulate, or without cross-
venules. Leaves
exstipulate.
Lamina margins entire, or
crenate, or
serrate. Leaves without a persistent basal
meristem.
General anatomy. Plants with ‘crystal sand’, or without ‘crystal sand’.
Leaf anatomy. Hydathodes commonly present.
Mucilaginous epidermis present, or absent.
Lamina dorsiventral (sometimes), or
isobilateral to centric (usually). Minor leaf veins with
phloem transfer cells (
Cotyledon, Crassula, Sedum), or without
phloem transfer cells (
Crassula, Sedum).
Stem anatomy. Cork cambium present; initially deep-seated (rarely), or superficial. Nodes
unilacunar, or
tri-lacunar.
Cortical bundles present (commonly), or absent.
Medullary bundles present (commonly), or absent. Internal
phloem absent. Secondary thickening mostly developing from a conventional cambial ring (very occasionally ‘anomalous’). ‘Included’
phloem absent.
Xylem with
libriform fibres; with vessels.
Vessel end-walls simple.
Reproductive type, pollination. Plants
hermaphrodite (usually). Floral
nectaries present.
Nectar secretion seemingly from the gynoecium (each carpel with a nectariferous appendage abaxially near the base, these usually in the form of scales, but large and petaloid in Monanthes). Entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in
cymes, or in
corymbs. The
terminal inflorescence unit
cymose.
Inflorescences cincinni or corymbs. Flowers small to medium-sized;
very regular (the formula being Kn, Cn, An+n, Gn — where n=3–30); (3–)5(–30)
merous;
cyclic;
pentacyclic. Floral receptacle not markedly hollowed.
Free hypanthium present (the flower usually weakly perigynous).
Hypogynous disk seemingly absent (i.e. the
nectariferous appendages being interpreted as
gynoecial).
Perianth with distinct calyx and corolla; (6–)10(–60); 2 whorled;
isomerous.
Calyx (3–)5(–30); 1 whorled; polysepalous; regular; persistent;
imbricate. Corolla (3–)5(–30); 1 whorled;
polypetalous (usually), or
gamopetalous (basally). Corolla lobes markedly longer than the tube.
Corolla imbricate; regular; white, or yellow, or pink, or purple.
Androecium (3–)5(–30). Androecial members free of the
perianth, or
adnate (to the
corolla tube/
hypanthium); free of one another (usually), or coherent (basally); when
connate, 1
adelphous; 2 whorled (usually), or 1 whorled.
Androecium exclusively of fertile
stamens (usually), or including
staminodes (e.g. some
Sempervivum species). Stamens (3–)5(–30);
diplostemonous (usually), or
isomerous with the
perianth (occasionally);
alternisepalous (when 2 whorled), or
oppositisepalous (when one whorled); both alternating with and opposite the
corolla members.
Anthers more or less basifixed;
non-versatile;
dehiscing via longitudinal slits;
latrorse (to slightly
introrse), or
introrse (
Crassula);
bilocular;
tetrasporangiate.
Endothecium developing fibrous thickenings. Anther
epidermis persistent.
Microsporogenesis simultaneous. The initial
microspore tetrads tetrahedral. Anther wall initially with more than one middle layer.
Tapetum glandular.
Pollen grains
aperturate; usually 3 aperturate; usually
colporate; 2-celled.
Gynoecium (3–)5(–30) carpelled.
Carpels isomerous with the
perianth.
Gynoecium apocarpous; eu-apocarpous to
semicarpous (the carpels often slightly united at the base); superior.
Carpel apically stigmatic (the style short or long); (1–)5–50 ovuled (usually ‘many’).
Placentation (sub) marginal. Stigmas wet type;
papillate; Group III type.
Ovules pendulous to horizontal;
biseriate; non-
arillate;
anatropous;
bitegmic;
crassinucellate. Outer
integument sometimes contributing to the
micropyle.
Embryo-sac development
Polygonum-type, or
Allium-type. Polar
nuclei fusing prior to
fertilization.
Antipodal cells formed; 3; not proliferating;
ephemeral (small).
Synergids pear-shaped.
Endosperm formation cellular.
Endosperm haustoria present;
chalazal.
Embryogeny caryophyllad.
Fruit non-fleshy;
an aggregate. The fruiting
carpels not coalescing (usually), or coalescing into a secondary
syncarp (this a capsule, in
Diamorpha). The fruiting
carpel dehiscent; a
follicle. Seeds endospermic.
Endosperm oily.
Cotyledons 2. Embryo
achlorophyllous (2/4); straight.
Seedling. Germination phanerocotylar.
Physiology, biochemistry. Cyanogenic, or not cyanogenic.
Alkaloids present (often), or absent.
Iridoids not detected.
Proanthocyanidins present, or absent; when present, cyanidin, or delphinidin, or cyanidin and delphinidin.
Flavonols present, or absent; when present, kaempferol, or kaempferol and quercetin, or kaempferol, quercetin, and myricetin.
Ellagic acid absent (5 species, 3 genera).
Saponins/
sapogenins present, or absent.
Aluminium accumulation not found.
CAM. CAM recorded directly in
Adromischus, Aeonium, Bryophyllum, Cotyledon, Crassula (including species with ‘aquatic CAM’),
Cremnophila, Diamorpha, Dudleya, Echeveria, Graptopetalum, Greenovia, Hasseanthus, Hylotelephium, Kalanchoe, Lenophyllum, Monanthes, Nanathus, Pachyphytum, Parvisedum, Rochea, Sedum, Sempervivum, Tylecodon, Umbilicus, Villadia.
Geography, cytology. Frigid zone to
tropical. Very widespread, but mainly in warm dry regions - especially in Southern
Africa.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Rosiflorae; Saxifragales. Cronquist’s Subclass Rosidae; Rosales. APG (1998) Eudicot; core Eudicot; Rosid; Saxifragales. Species 1500.
Genera about 40;
Adromisschus, Aeonium, Aichryson, Bryophyllum, Chiastophyllum, Cotyledon, Crassula, Cremnophila, Diamorpha, Dudleia, Echeveria, Graptopetalum, Greenovia, Hylotelephium, Hypagophytum, Jovibarba, Kalanchoë, Lenophyllum, Meterostachys, Monanthes, Mucizonia, Orostachys, Pachyphytum, Pagella, Parvisedum, Perrierosedum, Pistorinia, Pseudosedum, Rhodiola, Rochea, Rosularia, Sedum, Sempervivum, Sinocrassula, Telmissa, Thompsonella, Tylecodon, Umbilicus, Villadia.
Illustrations.1 Sempervivum arachnoideum.
Sedum,
Crassula,
Umbilicus. Technical details (
Sedum,
Crassula). Technical details (
Kalanchoe laciniata).
Quotations
There from his rocky pulpit, I heard cry
The stonecrop: See how loose to earth I grow,
And draw my juicy nurture from the sky
(Rev. R.W. Evans, quoted by Ann Pratt, ‘Wild Flowers’ (1857)
Cite this publication as: ‘L. Watson and M. J. Dallwitz (
1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 27th September
2000. http://biodiversity.uno.edu/delta/’. Dallwitz (
1980), Dallwitz, Paine and Zurcher (
1993,
1995,
2000), and Watson and Dallwitz (
1991) should also be cited (see References
2).
1 URLs for illustrations given in article
2 References
- http://www.keil.ukans.edu/delta/angio/www/refs.htm