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Acer saccharum subsp. nigrum - black, black sugar, or rock maple


Black maple is a close relative of sugar maple (A. saccharum), the two being difficult to distinguish, with the black supposedly having darker bark and less sharply defined leaf lobes. It is distinctly more southern in its range but has nevertheless grown well at Mustila from seed collected at Guelph in south Ontario in 1992. It is said to be very drought-tolerant, and hardy in both the heat and the cold of the American Midwest.

In America the black maple can grow up to 40 metres but in Finland remains considerably smaller. Like the sugar maple, it has showy autumn colour and its sap can be used to make maple syrup.


Acer pictum subsp. mayrii

This subspecies of the mono maple is said to grow only in Japan, and even there only in a small area. However, it came to Mustila from Sakhalin Island, where it also grows. It can be distinguished from mono maple by its rounded but almost always 5-lobed leaves, whereas the mono has 7 lobes. It is also easily confused with another close relative, the Cappadocian maple (A. cappadocicum), native to the mountainous parts of Caucasia.

In the wild, A. pictum subsp. mayrii grows about 10-15m high in snowy mountain areas. Planted, it is a beautiful round-headed tree, flowering in spring on bare branches before leaf-break. The inflorescence resembles that of the Norway maple (A. platanoides), both in size and in its yellow-green colour.

So far there has been little experience with growing this maple in Finland but hardy provenances are worth noting when the need is for the typically luxuriant and beautiful foliage of the Norway maple, but on a smaller tree. The leaves open bronze-red in spring, emphasising by their contrast the bright green of the flowers.


Acer caudatum subsp. ukurunduense - Ukurundu maple

The Ukurundu maple has a spreading, multi-stemmed, shrubby habit with layers of yellowish, finely hairy branches curving upwards and outwards. Gradually the bark on the branches changes to cinnamon brown and exfoliates in strips. In spring it flowers after leaf break with creamy white panicles; autumn colour varies from salmon-pink through orange-brown to violet.

Growing in the wild among the higher shrub layers of conifer forests, this maple is quite happy in shade. It is native to Japan and north-east Asia. In Finland, it can be mistaken for its American relative, mountain maple (A. spicatum). The latter has similar flower panicles but its leaves usually have only 3 lobes, compared with the 5 lobes of the Ukurundu, and mountain maple leaves are less hairy on their undersides. Also, mountain maple does not develop exfoliating bark, remaining smooth even when older.

Both these maples are extremely winter hardy, given suitable provenances, though there have been more problems growing the Ukurundu, at least at Mustila.


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