NATURAL OEDEES. 
259 
437. AcERACE^, the Maple Tribe. — Trees with opposite, sim- 
ple, rarely pinnate leaves. Fig. m 
Flowers often polyga- 
mous. Calyx divided 
into 5, occasionally 4-9 
parts. Petals as many 
as the lobes of the calyx, 
inserted round a hypo- 
gynous disk, or wanting. 
Oy<2?'^free,2-lobed; style 
1 ; stigmas 2 ; ovules pen- 
dulous, in pairs. Fruit 
a samara composed of 2- 
winged carpels, each 1- 
celled, 1 or 2 seeded. 
Seeds solitary, destitute 
of albumen. Embryo 
coiled. 
a. Properties : useful timber- 
trees ; the sap of A. saccharinum 
yields sugar. 
Genera. — Acer, Negundo. 
Fig. 183, a, Acer saccharinum (sugar -maple) ; branch of a staminate plant m 
flower 6, a staminate flower, enlarged ; c, a pistillate flower with the calyx lai(i 
open, showing the short stamens, disk, etc. ; d, the pistil of the same, the other 
organs removed ; e, the fruit, one carpel cut open to show the seed. 
438. SApmDACE^, the Soap-tree Tribe. — Trees or twining 
shrubs. Leaves alternate, compound, often marked with lines 
or pellucid dots. Flowers small, irregular. Sepals 4 or 5, dis- 
tinct, or cohering at the base. Petals 4-5, occasionally want- 
ing, alternate with the sepals. Stamens 8-10. Ovary 2 or 3 
celled ; ovules ascending or suspended. Fruit a capsule, or 
samara, or fleshy and indehiscent. Seeds usually with an aril, 
exalbuminous ; embryo coiled. In this order are included Hip- 
PocASTAN^ or Horse-chestnuts. 
a. Properties : sometimes used as a substitute for soap ; astringent and bitter. 
Genera. — Cardiospermum, Sapindus, Dodonea, iEsculus. 
439. Staphylace^, the Bladder-nut Tribe. — Shrubs with op- 
posite, pinnate leaves. Sepals 5, united at the base, colored 
Petals 5, alternate, aestivation imbricate. Stamens 5, alternate 
with the petals. Dish large, urceolate. Ova/ry 2-3-celled ; 
ovules usually ascending. Fruit membraneous or fleshy. Seeds 
vv^ith a bony testa, without albumen ; embryo straight ; cotyle- 
dons thick. 
a. Properties : sub-acrid, or bitter and astringent. 
Genus. — Staphylea. 
440. Celasteacej]:, the Spindle-tn^ee Tribe. — Small trrc^s or 
