160 FAMILIES OF FLOWERING PLANTS 
mens are 4-12; and the 2-lobed ovary becomes in fruit a familiar “key” 
or samara, differing greatly in shape. Maple wood is hard, of variable 
density and color; it is ordinarily susceptible of a fine polish, and plays 
an important part in cabinet making. 
Family Hippocastanaceae. Horse-chestnut Family. Contains two 
genera, Zsculus, with about 15 species, and Billia, with 2, the latter 
Mexican. They are trees or shrubs with palmately divided leaves and 
perfect, irregular flowers borne in large pyramidal panicles. The calyx 
is bell-shaped; petals 4 or 5, long-clawed; stamens 5-8; ovary 3-celled, 
becoming a leathery capsule containing 1-3 large shining seeds. 
The common horse-chestnut (4. Hippocastanwm) of our streets and 
, parks is a native of Asia, but 
has escaped from cultivation 
in many places in the East. 
The western buckeye (4. 
glabra) is well shown in the 
accompanying photograph 
(Fig. 140.) There are sev- 
eral other ornamental native 
species, some with red and 
some with yellow flowers. 
Family Sapindaceae. 
Soapberry Family. Con- 
tains about 120 genera and 
over 1000 species, of wide 
distribution in tropical and 
semitropical regions. They 
are trees or shrubs with 
Fig. 138. The bladder-nut (Svaphylea trifolia) show- mostly pinnate or palmate 
ing flowering branch and detached fruit. Original, leaves, and regular or irreg- 
ular, perfect or sometimes dioecious flowers. Calyx 4-5 lobed or di- 
vided; petals 3-5, borne on a fleshy disk, as are the 5-10 stamens; fruit 
a berry or a capsule, the latter sometimes bladdery-inflated, as in the 
balloon vine (Cardiospermum) of our gardens. 
Sapindus is a genus of about 10 species, one or two of which are 
found within our borders. They are called soapberries, from the fact 
that the-outer covering of the fruit contains a saponaceous principle 
used extensively in the tropics in place of ordinary soap. The hard 
round seeds of some species are used for making necklaces and rosa- 
ries. Serjania and Paullinia are two very large genera of climbing 
shrubs, common in tropical regions. The seeds of P. sorbilis, the gua- 
rana, are made into compressed cakes from which a cooling beverage is 
prepared, and form an extensive article of trade in Brazil. Litchi nuts, 
