242 
APIUM 
14 sp. cosmop. 3 in Brit, of which A. graveolens L., found in marshy 
places near the coast, is the celery. The wild plant is poisonous, but 
cultivation and the blanching (etiolation) of the leafstalks by heaping 
earth over them, renders the garden form innocuous. The two other 
sp. are common in ditches. 
Aplopappus Cass. {Haplopappus Endl.). Compositae (ill - ). 100 sp. 
W. Am. 
Apocaxpae (Benth. -Hooker). The 6th series of Monocotyledons (p. 136). 
Apocynaceae. Dicotyledons (Sympet. Contortae). 130 gen. and abt. 
1000 sp., mostly trop. A few are temp.; Vinca minor gives the N. 
limit in Eur. Erect plants are rare, the order consisting mainly of 
twining shrubs ; in the tropics many grow to large lianes. The stem 
has bi-collateral bundles; latex is always present. The leaves are 
simple, usually opp., entire, rarely with small interpetiolar stipules. 
The primary type of infl. is a panicle, but in its later branchings 
it sometimes goes over into a dichasial cyme or a cincinnus. Bracts 
and bracteoles are both present. 
Fir. $, regular, 5- or 4-merous. K (5), deeply lobed, quin- 
cuncial with odd sepal posterior; C (5), usually salver- or funnel- 
shaped, often hairy within, convolute (valvate in a few rare gen.); 
A 5, alternate with pets., epipetalous, with short included filaments; 
anther lobes full of pollen to the base, or empty at base and pro- 
longed into rigid spines. Disc usually present. Cpls. (2) or 2 
(united by style) or more, superior, 1- or 2-locular when syncarpous. 
Ovules 00 , anatropous, pendulous. Style usually simple with thick- 
ened head. Fruit a berry, or more often 2 follicles. Seeds usually 
flat and often with a crown of hairs serving for wind distribution. 
Endosperm or none ; embryo straight. 
In the common A. with a large stylar head the stigma is at the 
edge or under surface of the head and self- fertilisation is almost im- 
possible. A very interesting mechanism is found in Apocynum andro - 
saeinifolium. 
Classification and chief genera (after K. Schumann) : 
I. PLUMIEROIDEAE (sta. free or only loosely joined to stylar 
head; thecae full of pollen, rarely with spines; seeds usually 
without hairs) : 
1. Arduineae (syncarpous; style not split at base): Arduina, 
Allamanda, Landolphia. 
2. Pleiocarpeae (apocarpous ; style split at base ; more than 
2 cpls.) : Pleiocarpa. 
3. Plumiereae (ditto; 2 cpls.): Plumiera, Amsonia, Vinca, 
Tabernaemontana, Cerbera. 
II. ECHITOIDEAE (sta. firmly joined to stylar head; thecae 
empty at base, and with spines ; seeds hairy) : 
4. Echitideae (anthers included): Apocynum, Nerium, Stro- 
phanthus, Dipladenia. 
