Platanaceae
Large, deciduous, monoecious trees; bark pale and usually exfoliating in thin plates. Lvs alternate, simple, palmately veined and palmately lobed; petiole dilated at base and enclosing bud; stipules often large, caducous. Infl. of pendulous strings with 1-12 dense globose heads of fls; heads either ♂ or ♀, sessile or pedunculate. ♂ heads: bracts 0; calyx 0; corolla 0; stamens 3-4 or numerous depending on interpretation, with subsessile anthers, each with a minute scale. ♀ heads: bracts linear; calyx 0; corolla 0; carpels 6-9 or numerous depending on interpretation, free, subsessile; styles persistent; stigma on inner side of style; ovary 1-celled, with 1-(2) pendulous ovules. Fr. a globose head composed of numerous 1-seeded, indehiscent, angled, obconic achenes or nutlets, surrounded by long hairs. Seed with thin endosperm; cotyledons often unequal.
1 genus, 8-10 spp., N. America and S.E. Europe to S.W. Asia, 1 doubtful sp. in Indochina.
The parents of London plane are P. occidentalis L. and P. orientalis L., both of which grow in N.Z., but are much less common than the hybrid. The 3 planes are distinguished by the degree of lobing of the lvs and the number of fl. heads to each infl. P. × acerifolia has been known since the 17th century in Europe where it originated. A few authorities use the earlier name P. × hispanica Muenchh., but there remains some doubt as what hybrid this name correctly applies.
