200 CONTRIBUTIONS FROM THE NATIOISTAL HERBARIUM. 



96. STAPHYLEACEAE. Bladdernut Family. 



1. STAPH YIEA L. 

 1. Staphylea trifolia L. Bladdernut. 



Moist woods. Apr.-May. Eastern U. S. 



Several species of Aesculus, of the Aesculaceae, are cultivated in parks and along 

 streets. They are trees with palmately compound leaves of 5-9 leaflets, conspicuous 

 panicles of white, yellow, or pink flowers, and large smooth seeds. The most common 

 is A. hippocastanum L., the horse chestnut. 



97. ACEEACEAE. Maple Family. 



Leaves simple; plants with perfect flowers; twigs reddish 1. ACER. 



Leaves pinnately compound; plants dioecious; twigs bright green 2. RULAC. 



1. ACER L. Maple. 



Several exotic species of maples are cultivated as shade trees, the more common 

 being: A. pseudo-platanus L., the sycamore maple, a large tree with drooping racemes, 

 woolly ovaries, and deeply 3-5-lobed leaves; A. platanoidts L., the Norway maple, a 

 large tree with flowers in corymbs, and shallowly 5-7-lobed leaves; A. tartaricum L., 

 a shrub with roundish, scarcely lobed leaves; A. campestre L., a small tree with 

 small 3-5-lobed leaves, 3.5-7.5 cm. long. 



Lobes of the leaves meeting in an evenly rounded curve; flowers appearing with the 

 leaves, green, hanging from long stalks, these often 5 cm. long; fruit maturing 

 in summer; body of each fruit distinctly less than twice the length of its scar. 



l.A. sacchanim. 

 Lobes of the leaves meeting at an angle; flowers appearing before the leaves, red or 

 yellow, in close clusters on the twigs, the stalks of the pistillate flowers, however, 

 elongating with the development of the fruit; fruit maturing in May or late April; 

 body of each fruit twice the length of its scar or more. 

 Leaf sinuses (the space between the lobes) intruded less than half the length of the 

 lateral lobes, approximately right-angled, the sides nearly straight; minute 

 petals present in the flower, in addition to the calyx lobes; fruit without hairi- 

 ness from the first, 1.5-2.5 cm. long when ripe 2. A. rubrum. 



Leaf sinuses intruded more than half the length of the lateral lobes, the sides much 

 curved outward before meeting at the angle; flower with calyx lobes only, no 

 petals; fruit woolly when young, retaining a scattered pubescence until matu- 

 rity, 5-7 cm. long when ripe 3. A. saccharinum. 



1. Acer saccharum Marsh. Sugar maple. 

 Rich woods along the Potomac; infrequent. May. Northern states and south- 

 ward in the mountains. (A. saccharinum Wang.) 



2. Acer rubrum L. Red maple. 

 Swamps and moist woods; common. Feb.-Apr. Eastern U. S. 



Also called swamp maple. 



3. Acer saccharinum L. Silver maple. 

 River banks; frequent. Jan.-March. Eastern U. S. {A. dasycarpum'Ehih.) 

 One of the earliest trees to flower in the spring. 



2. RULAC Adans. 



1. Rulac negundo (L.) Hitchc. Boxeldek. 



Low moist woods; common. Apr. Eastern U. S. {Acer negundo L.; Negundo 

 aceroides Moench.) 



