A tall tree with laxly pendulous lower branches, upper branches not contorted as in the London plane. Leaves rather thin, light green, mostly 10 to 12 in. wide, sometimes as much as 16 in. wide, commonly five-lobed, sinuses variable, from broad and shallow to deep and narrow, lobes finely tapered and edged with fairly regular slenderly tipped teeth, base mostly truncate and never deeply cordate, with or without a central wedge, and sometimes distinctly tapered at the base, especially on young trees; the secondary veins running out to the tips of the fourth and fifth lobes are usually directed forward, instead of spreading more or less horizontally as in the London plane; the two main veins, i.e., those running to the tips of the two upper lobes, meet the midrib at the base of the blade or slightly above it. The undersurface of the leaf is at first often as woolly as in P. occidentalis and the hairs on the veins persist rather longer than in the London plane. The petiole is 21⁄4 to 31⁄2 in. long. The fruit-balls, not freely produced, are solitary, in pairs or threes; achene with an almost glabrous body.
This striking plane was received at Kew in 1878 from the Belgian nurseryman Van Houtte under the name “P. californica” and was sold under that name by other continental nurseries, and also by Lee’s nursery, Hammersmith. It was also known as “P. racemosa”, and this seems to have been the name under which it has been generally known in this country, at least in commerce. But P. racemosa Nutt. is the California plane, to which ‘Augustine Henry’ bears no resemblance at all, and P. californica Benth. is a synonymous name of this species. Dr Henry considered that “P. californica” was none other than the Spanish plane of Miller, and in his paper on the London plane he describes and figures it under the name P. hispanica Muenchh. But it is impossible to accept this conclusion, for which Henry offered no evidence beyond the general agreement between the Kew trees and Miller’s scanty description of the Spanish plane. However, it was he who first gave a full account of this plane and first called attention to its merits. It is therefore appropriate that it should bear his name. P. ‘Augustine Henry’ is discussed and figured by Henry (as P. hispanica Muenchh.) in Proc. Roy. Ir. Acad., Vol. 35 (B), pp. 18-19; pl VII, fig. 5; pl. IV, pl. IX, fig. 9, no. 4. The reference-tree of this clone grows at Kew by the Azalea Garden, near the Iron Drinking Fountain (No. 10, Gardens Accession No. 0073.10001). It measures 98 × 101⁄4 ft (1973).
Even without a close examination of the leaves, ‘Augustine Henry’ can be distinguished from the London plane by the laxer lower branches, the smoother, more freely flaking trunk, the usually better developed central stem, and the different colour of the foliage, which verges on sea-green. The leaves are much more numerously and more elegantly toothed, and there is a tendency for the blades to droop at the edges and thus appear more attenuated at the base than in fact they are when flattened into the horizontal plane. The leaves are also on the average much larger than in the London plane. In addition to the reference-tree at Kew mentioned above, there is another of the same age nearby, in Syon Vista, which is very similar, allowing for its sunnier position, and is probably of the same clone. Some have been noticed in central London, the finest being one in St James’s Park, on the slope north of the bridge, to the right of the path leading from The Mall to Queen Anne’s Gate.