222 
ACER 
scale is the equivalent, not of the whole leaf, but of the leaf base. 
In Negundo, often united to A., there are no scales, but the bud 
is protected by the base of the petiole of the leaf in whose axil it 
arises. 
The leaves of the maple commonly exhibit vamish-like smears, of 
sticky consistence, known as honey-dew. This is the excretion of the 
aphides which live on the leaves ; the insect bores holes into the 
tissues, sucks their juices, and ejects a drop of honey-dew on an 
average once in half-an-hour. In passing under a tree infested with 
aphides one may sometimes feel the drops falling like a fine rain (see 
Pithecolobium). The fluid is rich in sugar. When the dew falls the 
hygroscopic honey-dew takes it up and spreads over the leaf ; then 
later in the day evaporation reduces it to the state of a varnish on the 
leaf surface, which aids in checking transpiration. Many other trees 
exhibit this phenomenon, e.g. lime, beech, oak, &c. (see Biisgen, Der 
Honigthau, Jena: Fischer). 
Firs, in racemes, sometimes contracted to corymbs or umbels, 
regular, polygamous, not very conspicuous. The formula is usually 
K5, C5, A4 + 4, G (2). There is usually a well-marked honey- 
secreting disc. Apetaly occurs in some sp. 3 cpls. are frequently 
met with, especially in the end fir. of a raceme. The $ firs, are prot- 
androus, but the fertilisation methods and still more the sex-distribu- 
tions and their causes, deserve further investigation. 
In germination, the long green cotyledons come above the soil 
almost at once, and perform assimilatory duties. 
A. saccharum Marshall (A. saccharinum Wangenh.) and other sp. 
of the E. U. S. yield maple sugar, obtained by boring holes in the 
tree in February and March and collecting and evaporating the 
escaping juice. Many sp. yield good timber. A number of Japanese 
sp., with prettily shaped or variegated leaves, are cultivated as orna- 
mental shrubs. 
Aceraceae. Dicotyledons (Archichl. Sapindales). 3 gen. (Acer, Ne- 
gundo, Dipteronia) with 1 12 sp. N. temp. (esp. in hills) and trop. 
mts. Trees and shrubs; leaves opp., petiolate, exstip., simple entire 
or more often palmately lobed or compound. Infl. racemose, corym- 
bose, or fasciculate. 
Firs, regular, andromonoecious, androdioecious, dioecious, &c., 
5-4-merous, usually dichlamydeous. Disc annular or lobed or reduced 
to teeth, rarely absent. A. 4 — 10, usually 8; $ fir. with rudimentary 
G. G (2), 2-loc., laterally compressed; styles 2, free or joined below; 
ovules 2 in each loc. , orthotropous to anatropous, with dorsal raphe. 
Fruit of 2 samaras, separating when ripe. Seeds usually solitary, 
exalbuminous, the cotyledons irregularly folded. Many sp. yield 
good timber, sugar, &c. (cf. Acer). Placed in Aesculinae by Warming, 
united to Sapindaceae by Benth.-Hooker. 
Aceranthus Morr. et Dene. Berberidaceae. 3 sp. Chi., Japan. United 
to Epimedium in Nat. PJi. 
