The flower is generally perfect, regular and polypetalous, usually
_perigynous_ or _epigynous_, _eucyclic_ and 5-merous; most frequently
S5, P5, A5 + 5 or 5 + 0 and G=2=-5, but other numbers are found,
especially 4; the flowers are very frequently obdiplostemonous. The
calyx is sometimes large and the corolla small; the carpels in some
are entirely free, in others more or less united. Endosperm is found
in the majority. ~The hypogynous forms approach the Cistifloræ, the
others the following families, especially the Rosifloræ. This family
is not, upon the whole, so well defined and natural as most of the
others. The Saxifragaceæ proper, approach very near to the Rosaceæ,
especially _Spiræa_, and form a transition to it. The forms with
opposite leaves, as _Philadelphus_, etc., approach the Myrtifloræ, just
as the Escalloniæ appear to be closely allied to Bicornes, especially
_Vacciniaceæ_. Finally through _Pittosporaceæ_, they pass over to the
Frangulinæ. The family terminates in very reduced forms, on the one
hand in the arborescent orders with crowded inflorescences, on the
other perhaps in the very remarkable order _Podostemaceæ_.~
[Illustration: FIG. 487.--Diagram of a 6-merous flower (_Sedum
hispanicum_): _w_ branch of scorpioid cyme in the axil of the
bracteole β.]
Order 1. =Crassulaceæ.= Nearly all are herbs or small shrubs with
round, succulent branches and scattered, _fleshy_, often more or less
round leaves, which are very rarely incised, and never have stipules.
The flowers are generally borne in dichasia or unipared scorpioid
cymes, which again may be arranged in racemes, umbels, etc.; they are
regular, ☿, hypogynous or perigynous, and most frequently have free
sepals and petals (gamopetalous corollas with sessile stamens are found
in _Cotyledon_, _Bryophyllum_, _Echeveria_, and others); the floral
formula is Sn, Pn, An + n, Gn, where n may have very different values,
partly depending upon the size of the flower (_e.g._ 4–7 in _Sedum_,
Fig. 487; 6–30 in _Sempervivum_; 4 in _Rhodiola_, _Bryophyllum_,
and _Kalanchoë_; 5 in _Echeveria_, _Umbilicus_, _Cotyledon_). The
carpels are _free_ and are _placed opposite the petals_ (Fig. 487).
Fruit a _syncarp composed of follicles_ containing many, small seeds
without endosperm. Outside each carpel is found a small, nectariferous
scale (Fig. 487). ~The northern genus, _Rhodiola_, is diœcious. The
petal-stamens are wanting in some (_Crassula_, _Bulliarda_, and
others). The floral-leaves are very often displaced upon their axillary
branches. A multicarpellary gynœceum also occurs.~
_Sedum_ (Stonecrop) is generally 5-merous with 10 stamens; _Sempervivum
tectorum_ (House-leek), 12-merous, and with 24 stamens. ~The leaves
of _Bryophyllum calycinum_ very readily form buds, and also frequently
exude water from the edges.~
485 species; especially Temp. (Cape, Europe). Principally used
as ornamental plants.
Order 2. =Saxifragaceæ.= The flowers are 4–5-merous with =2= (-3)
carpels, most frequently: S5, P5, A5 + 5 (obdiplostemonous), G2. They
are regular, ☿, polypetalous, hypogynous, perigynous or most frequently
_more or less epigynous_ (Fig. 488). The carpels may be individually
quite free, but are more frequently united at the base, or the entire
portion enclosing the ovules is united into a 1- or 2-locular ovary, the
styles, however, are always free. _Fruit a capsule_ with many seeds;
endosperm present.--They are herbs, most frequently with _scattered_
leaves without stipules; but the leaf-base is broad. The inflorescences
are most frequently cymose, and a displacement of the floral-leaves is
frequent (_e.g._ _Chrysosplenium_).--~Some _Saxifraga_-species, _e.g._
_S. sarmentosa_, have irregular flower with an _oblique_ plane of
symmetry. The petal-stamens in some may be wanting: _Heuchera_, species
of _Saxifraga_ and _Mitella_. The corolla is wanting in others.~
_Saxifraga_ (Saxifrage): S5, P5, A5 + 5, G2 (Fig. 488); capsule
bilocular, opening along the ventral suture between the 2 persistent
styles. ~_S. granulata_ has small tubers at the base of the
stem.~--_Chrysosplenium_ (Golden Saxifrage): 4 sepals, _no corolla_, 4
+ 4 stamens; 1-locular capsule.
Protandry is most frequently found in _Saxifraga_, with the
stamens successively bending towards the gynœceum; protogyny
is more rare. In other genera there is protogyny without any
movement of the stamens; _Chrysosplenium_ is homogamous.--About
300 species; mostly in temperate climates. _Saxifraga_ is
especially Alpine. _S. crassifolia_ and other species, _Hoteia
japonica_, _Tellima_, etc., are ornamental plants.
[Illustration: FIG. 488.--_Saxifraga granulata._ Longitudinal
section of flower.]