Family 14. PLATANACEAE 
By HENRY ALLAN GLEASON 
Trees or shrubs, with exfoliating bark. Leaves broad, alternate, stipulate, 
long-petioled, palmately 3-5-nerved and lobed, cuneate to cordate at the base. 
Stipules membranous, lobed or entire, connate, deciduous. Petioles dilated at 
the base and covering the buds. Inflorescence of spherical unisexual heads, 
which are racemose or spicate, or solitary and terminal, on long slender per- 
sistent peduncles. Flowers monoecious, typically isomerous. Sepals 3 or 4, 
or rarely 6, spreading, hairy without. Petals alternating with the sepals, 
spatulate, membranous, lobed or emarginate. Stamens in do flowers typically 
alternate with the petals ; filaments short ; anthers linear, the connective dilated 
at the apex and covering the anthers. Staminodes in 2? flowers caducous. 
Carpels 3 or 4, distinct,-opposite the petals and adherent to them ; ovary linear ; 
style linear, recurved at the tip, and stigmatose on the inner side. Ovule 1 
(rarely 2), pendulous, orthotropous. Fruit an achene, indehiscent, linear, 4- 
sided, surrounded by long hairs at the base, truncate and tipped with the per- 
sistent style, aggregated in dense spherical heads. 
1. PLATANUS L,. Sp. Pl. 999. 1753. 
Characters of the family. 
Type species, Platanus orientalis \. 
Heads 3-5 on each peduncle. 
Leaves broadly rounded at base, the lobes 3, all erect. 1. P. Lindeniana. 
Leaves truncate to cordate at base, the lobes 3-5, divergent. 
Heads sessile; fruiting style 2-3 mm. long. 2. P. racemosa, 
Heads pedicelled ; fruiting style 1-2 mm. long. 3. P. Wrightit. 
Heads 1 or 2 on each peduncle. 
Leaves persistently and closely cinereous beneath. 4. P. mexicana, 
Leaves green and eventually glabrous beneath. 
Leaf-lobes entire. 5. PB. glabrata, 
Leaf-lobes with coarse salient teeth. 6. £. occidentalis. 
1. Platanus Lindeniana Mart. & Gal. Bull. Acad. Roy. 
Bruxelles 10': 342. 1843. 
A tree, 30-40 m. high; young twigs and petioles ferruginous-pubescent, becoming gla- 
brate with age; leaves broadly rounded at base, 3-lobed, 3-nerved, entire or with a few 
scattered teeth, 12-18 cm. long and broad, densely tomentose above when young, glabrous 
at maturity, persistently and softly ferruginous-tomentose beneath ; lobes triangular, acute, 
erect, the middle one about as long as broad and 0.3-0.5 as long asthe blade; petioles 2-5 
cm. long; stipules bifid; staminate heads 6-10 mm. in diameter; pistillate heads sessile, 
2.5 cm. in diameter at maturity ; achene 6-8 mm. long, about equaled by the basal hairs, 
glabrous below, pubescent at the tip, abruptly narrowed into a persistent style 2-3 mm. 
long. 
TYPE LOCALITY: Jalapa, Mexico. 
DISTRIBUTION: Central Mexico. 
2. Platanus racemosa Nutt. N. Am. Sylva 1: 47. 1842. 
Platanus occidentalis H. & A. Bot. Beech. Voy. 160. 1833. Not P, occidentaits L,. 1753. 
Plaianus californica Benth. Bot. Voy. Sulph. 54. 1844. 
Platanus mexicana Torr. in Sitgreaves, Rep. Exp. 172. 1853. Not P. mexicana Moric. 1830. 
VOLUME 22, Part 3, 1908] 227 
