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APOCYNACEAE 
5. Parsonsieae { anthers excluded) : Parsonsia, Lyonsia. 
[Placed in Gentianales by B. and H.; Contortae by Warming.] 
Apocynum (Tourn.) Linn. Apocynaceae (11. 4). 3 sp. Eur., As., 
N. Am. Of these the most interesting is A . androsaemifolium L., a 
shrub often found in gardens under the name “American fly-trap,” 
given to it because large numbers of flies are caught by the firs. The 
mechanism resembles that of Asclepiadaceae. The ovary is crowned 
by a disc, stigmatic on the lower side and surrounded by the rigid 
lignified stamens. Honey is secreted at the base of the stamens 
and an insect in withdrawing its proboscis usually brings it up the 
narrow slit between two stamens. At the base of this is a drop 
of cement and higher up the anthers dehisce laterally; thus the insect 
withdraws the pollen on its proboscis, but considerable strength is 
required and small insects are usually held fast. On a second visit 
the pollen is scraped off upon the stigmatic surface. The seeds are 
crowned with hairs for wind carriage. 
Aponogeton Linn. f. Aponogetonaceae. 15 sp. Afr., Madag., As., 
Austr. Water-plants with sympodial tuberous rhizomes. Leaves 
usually floating, but submerged ones occur in some sp., e.g. A. 
(Ouvirandra) fenestrale Hook. f. Here the whole tissue of the leaf 
between the veins breaks up as the leaf grows, leaving a network of 
veins with holes between them. Close round the veins is a little 
green tissue serving assimilatory purposes. The interior tissue does 
not contain the intercellular spaces characteristic of most water-plants, 
and Goebel (. PflanzmbioL Schild. II. p. 319) suggests that this is 
because the holes in the leaf render all parts of it easily accessible to 
the water with its dissolved gases. Young leaves in the bud show no 
trace of this phenomenon. [See p. 160.] 
The firs, project above the water, and are arranged in spikes ; the 
spathe is early thrown off. Some sp. have a perianth of 3 leaves, but 
usually it is of only 2 leaves or even 1, as in the Cape pond-weed 
(A. distachyum Thunb.) now so much cultivated for its sweet-scented 
firs. The one leaf is attached to the axis of the spike by a broad 
base and looks like a bract. In this sp. the sta. are 00 and cpls. 
3 — 6, but in most we find A 3 + 3, G 3. Ovules 2 or 00 in each, 
anatropous, erect. Fruit leathery. Embryo straight. 
Aponogetonaceae. Monocotyledons (Helobieae). Only genus Apono- 
geton (</•&.). They are distinguished from Potamogetonaceae by the 
coloured perianth and straight embryo, from Juncaginaceae by the 
perianth and the sympodial structure. Benth. -Hooker place them 
in Naiadaceae with several other orders here treated separately. 
Apostasia Blume. Orchidaceae (1). 4 sp. E. Ind. to Austr. Fir. 
almost regular, diandrous; ovary 3-locular. 
Aquifoliaceae Dicotyledons (Archichl. Sapindales). 5 gen. 180 sp. 
chiefly Amer. Shrubs and trees with leathery alt. leaves and minute 
stipules. Infl. cymose. Fir. regular, unisexual, 3 — 6-merous with no 
