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Article from Bean's Trees and Shrubs Hardy in the British Isles
'Acer pentapotamicum' from the website Trees and Shrubs Online (treesandshrubsonline.
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A small tree with a smooth greyish bark. Leaves three-lobed, 11⁄4 to 4 in. long, 21⁄2 to 6 in. wide, truncate or heart-shaped at the base, pale green on both sides, glabrous when mature except for axillary tufts of hairs on the veins beneath; lobes extending about half-way to the centre of the leaf, ovate, tapered at the apex, bluntly toothed. Flowers in short corymbs. Wings of fruit diverging at an acute angle; keys about 1 in. long; nutlets glabrous.
Native of the N.W. Himalaya, where it grows in dry, open woodland in the basins of almost all the great rivers from the Jhelam to the Sutlej – hence the epithet pentapotamicum (of the five rivers), which, owing to a misprint or slip of the pen, was given as “pentapomicum” in the original description. This species is perhaps not in cultivation, though the name is sometimes encountered on labels. The tree at Kew raised from seed purporting to be of this species proves to be A. acuminatum and this is also true of one at Borde Hill, received from a nursery. Others grown in Ireland as A. pentapotamicum are also not the true species.
A. pentapotamicum was placed by Pax in section Spicata but its affinities within this group are uncertain.
In the classification adopted by de Jong in Sex Expression in Acer, this species is grouped with A. pilosum in series Pubescentia of the section Platanoidea.
The five rivers to which the specific epithet refers are the five rivers of the Punjab (in its older regional sense), on the upper reaches of which the species occurs. It might have been added that the word Punjab derives from Persian and ultimately Sanskrit words meaning ‘five waters’ or ‘five rivers’. The epithet ‘pentapotamicum’ is thus no more than a scholarly version of the more usual ‘punjabense’. However, it is arguable that the nonsensical mis-spelling ‘pentapomicum’ actually used by Brandis when describing the species has been accepted by later authorities, and that it should therefore be retained.