CENTROSPERMAE 
150 
Subclass 3. CENTROSPERMAE 
Centrospermae Engler Fuhrer Bot. Gart. Breslau 36 (1886) as an order; in Engler und Prantl Pflanzenfam. 
Nachtr. 346 (1897) including group “c,” as an order; Syll. ed. 2, no (1898) including group “c,” as an order; 
Curvembryosae Lindley Nat. Syst. ed. 2, 206 (1836) partim. 
Although the range of floral structure in the Centrospermae is very great, we believe the group to be a very natural one. 
The different orders probably represent diverging lines of development from a primitive apocarpous stock. Apocarpous fruits 
still occur in some exotic forms of the Phytolaccaceae ; and Mesembryanthemum, which is naturalised in this country, 
represents the extreme limits of specialisation in this order. The remaining orders are closely allied ; and specialised forms 
occur in the tribe Diantheae. These orders too are related to the Primulales\ and in future systems of classification, it may 
be that the Centrospermae and the Primulales will be placed much closer together than at present. 
In a general way, it may be said that the earlier and probably more primitive members of the Centrospermae are 
characterised by alternate leaves, by a monochlamydeous and sepaloid perianth, by a single whorl of antisepalous stamens, by 
free carpels or a unilocular indehiscent one-seeded fruit with basal placentation, and by anemophilous pollination, whilst the 
later and probably more specialised members of the group possess opposite leaves, a heterochlamydeous perianth, an 
obdiplostemonous androecium, a unilocular dehiscent many-seeded and rarely subseptate fruit with free-central or central 
placentation, and by entomophilous pollination. 
For characters, see page 2. 
Orders of Centrospermae 
Order 1. # Phytolaccales (see below). Leaves alternate or opposite. Flowers bracteate, bracts 
often coloured and simulating a calyx, the parts sometimes spirally arranged. Perianth mono- 
chlamydeous, sepaloid. Stamens 3 — 00, outer ones sometimes barren and petaloid. Carpels 1 — 00, 
almost apocarpous or (usually) syncarpous. Fruit an achene, nut, drupe, or capsule. Placentation 
basal, axile, or parietal. 
Order 2. Chenopodiales (p. 152). Leaves usually alternate, rarely opposite. Flowers & bracteate 
or bracteate. Perianth monochlamydeous, sepaloid, persistent, with 1 — 5 usually 4 — 5 segments, 
rarely absent. Stamens usually equal in number to the perianth-segments, rarely fewer, usually 
antisepalous. Fruit usually an achene, rarely a primitive 1 -seeded pyxidium. Placentation basal. 
Order 3. Portulaccales (see Vol. III). Leaves alternate or opposite, stipulate or not. Flowers 
ebracteate or bibracteate. Perianth dichlamydeous. Calyx consisting of 2 opposite sepals (sometimes 
regarded as bracteoles). Corolla with 4 — 5 petals, polypetalous or gamopetalous. Stamens 4 — 5 
and antipetalous, or twice this number. 
Order 4. Dianthales (see Vol. III). Leaves usually entire, usually opposite and decussate, 
stipulate or not. Flowers usually actinomorphic and entomophilous. Perianth monochlamydeous or 
(usually) heterochlamydeous. Stamens usually 10, in 2 whorls, more rarely 3 — 5, outer whorl often 
antisepalous. Ovary with 1 — 5 carpels, unilocular or sometimes with more or less definite traces of 
septa. Placentation basal, free-central, or central. Fruit an achene or (usually) a capsule. 
Order i. *PH YTOLACCALES 
Phytolaccales nobis; Phytolaccineae Engler Pflanzenfam. Nachtr. 347 (1897). 
For characters, see above. Only family represented in this country : — *Aizoaceae. 
Family 1. *AIZOACEAE 
Aizoaceae A. Braun in Ascherson Ft. Prov. Brandenb. i, 60 (1864) ; Pax in Engler und Prantl Pflanzenfam. 
iii, pt. ib, 33 (1889); Fico'ideae Jussieu Gen. PI. 315 (1789) partim; Bentham and Hooker Gen. PI. i, 851 
(1867); Fico'ideae or Mesembryaceae Lindley Nat. Syst. ed. 2, 56 (1836) including Tetragoniaceae p. 209. 
Shrubs or herbs. Leaves simple, usually opposite, succulent. Stipules absent or scarious. 
Inflorescence cymose or solitary and terminal. Perianth monochlamydeous, sepaloid, with 4 — 8, 
usually 5, segments ; segments united or apparently free, the median one posterior, equal or unequal. 
Androecium often consisting of stamens and petaloid staminodes. Stamens 5 — 00 . Ovary superior to 
