The UKBA Glossary of Bonsai Terms - A















the more diverse of the two superorders of “mites” with over 32,000 described species are found in 351 families, and an estimated total of 440,000 to 929,000 species occur, including undescribed species.







see Acari







genus of trees including “Maples” and “Sycamore” with some 128 species and thousands of hybrids.

Acer Buergerianum






“Trident Maple” – naturally a small to medium sized deciduous tree reaching a height of 5m to 20m with a trunk up to 0.5m diameter. The leaves are in opposite pairs, 25mm to 80mm long (excluding the 20mm to 50mm petiole) and 35mm to 65mm broad, hard, glossy dark green above, paler below, usually with three lobes; on mature trees the lobes forward-pointing and with smooth margins, on young trees with more spreading lobes and serrated margins.  The flowers are produced in spring, yellow-green, in pendulous corymbs; they are small, with five greenish sepals and five yellow-white petals about 2mm long, and eight stamens. The fruit is a samara with two winged seeds, each seed 4mm to 7mm diameter, with a 15mm wing; the wings are forward-pointing and often overlapping each other.  A species of maple native to eastern China (from Shandong west to south eastern Gansu, south to Guangdong, and southwest to Sichuan), Taiwan and Japan.

Acer Campestre






“Field Maple” – naturally a deciduous tree reaching 15m to 25m tall, with a trunk up to 1.0m diameter, with finely fissured, often somewhat corky bark. The shoots are brown, with dark brown winter buds. The leaves are in opposite pairs, 50mm to 160mm long (including the 30mm to 90mm petiole) and 50mm to 100mm broad, with five blunt, rounded lobes with a smooth margin. Usually monoecious, the flowers are produced in spring at the same time as the leaves open, yellow-green, in erect clusters 40mm to 60mm across, and are insect-pollinated. The fruit is a samara with two winged achenes aligned at 180°, each achene is 8mm to 10mm wide, flat, with a 20mm wing.  A flowering plant species in the “soapberry” and “lychee” family Sapindaceae. It is native to much of Europe, the British Isles, southwest Asia from Turkey to the Caucasus, and north Africa in the Atlas Mountains.

Acer grandidentatum






“bigtooth maple”

Acer nigrum






“black maple”

Acer Palmatum






“Japanese Maple” – naturally a deciduous shrub or small tree reaching heights of 6m to 10m, rarely 16 metres, often growing as an understory plant in shady woodlands. It may have multiple trunks joining close to the ground.  In habit, its canopy often takes on a dome-like form, especially when mature.  The leaves are 40mm to 120mm long and wide, palmately lobed with five, seven, or nine acutely pointed lobes. The flowers are produced in small cymes, the individual flowers with five red or purple sepals and five whitish petals. The fruit is a pair of winged samaras, each samara 20mm to 30mm long with a 6mm to 8mm seed. The seeds of Acer palmatum and similar species require stratification in order to germinate.

Acer Platanoides






“Norway Maple” – naturally a deciduous tree, growing to between 20m and 30m tall with a trunk up to 1.5m in diameter, and a broad, rounded crown.  The bark is grey-brown and shallowly grooved. Unlike many other maples, mature trees do not tend to develop a shaggy bark. The shoots are green at first, soon becoming pale brown. The winter buds are shiny red-brown.  The leaves are opposite, palmately lobed with five lobes, 70mm to 140mm long and 8omm to 20mm (rarely 250mm) across; the lobes each bear one to three side teeth, and an otherwise smooth margin. The leaf petiole is 8mm to 200mm long and secretes a milky juice when broken. The autumn colour is usually yellow, occasionally orange-red.  The flowers are in corymbs of 150mm to 300mm together, yellow to yellow-green with five sepals and five petals 3mm to 4mm long; flowering occurs in early spring before the new leaves emerge. The fruit is a double samara with two winged seeds. the seeds are disc-shaped, strongly flattened, 10mm to 15mm across and 3mm thick. The wings are 3omm to 50mm long, widely spread, approaching a 180° angle. It typically produces a large quantity of viable seeds.

Acer pseudoplatanus






“Sycamore” – naturally a large, broadleaved deciduous tree that reaches 20m to 35m tall at maturity, the branches forming a broad, domed crown. The bark of young trees is smooth and grey but becomes rougher with age and breaks up into scales, exposing the pale-brown-to-pinkish inner bark.  They shoot tip in winter with a green terminal bud and paired green lateral buds.  The buds are produced in opposite pairs, ovoid (approximately oval in shape) and pointed, with the bud scales (the modified leaves that enclose and protect the bud) green, edged in dark brown and with dark brown tips, 5mm to 10mm.  When the leaves are shed, they leave horseshoe shaped marks called leaf scars on the stem. The leaves are opposite, large, 100mm to 250mm long and broad, palmate with 5 pointed lobes that are coarsely toothed or serrated. They have a leathery texture with thick veins protruding on the underside. They are dark green in colour with a paler underside. Some cultivars have purple-tinged or yellowish leaves. The leaf stalk or petiole is 50mm to 150mm long, is often tinged red with no stipules or leaf-like structures at the base.  The monoecious (or bisexual) yellow-green flowers are produced after the leaves in early summer, in May or June in the UK  on pendulous panicles 100mm to 2000mm long with about 60–100 flowers on each stalk.  The fruits are paired winged seeds or samaras, the seeds 5mm to 10mmin diameter, each with a wing 20mm to 40mm long developed as an extension of the ovary wall.  The wings are held at about right angles to each other, distinguishing them from those of A. platanoides and A. campestre, in which the wings are almost opposite and from those of A. saccharum, in which they are almost parallel. When shed, the wing of the samara catches the wind and rotates the fruit as it falls, slowing its descent and enabling the wind to disperse it further from the parent tree. The seeds are mature in autumn about four months after pollination.

Acer saccharum







“Sugar Maple” or “Rock Maple” – naturally a deciduous tree normally reaching heights of 25m to 35m and exceptionally up to 45m. A 10-year-old tree is typically about 5m tall. When healthy, the A. saccharum can live for over 400 years.  The leaves are deciduous, up to 200mm long and equally wide, with five palmate lobes. The basal lobes are relatively small, while the upper lobes are larger and deeply notched. In contrast with the angular notching of the A. saccharum, however, the notches tend to be rounded at their interior. The fall colour is often spectacular, ranging from bright yellow on some trees through orange to fluorescent red-orange on others. A. saccharum also have a tendency to colour unevenly in fall. In some trees, all colours above can be seen at the same time. They also share a tendency with red maples for certain parts of a mature tree to change colour weeks ahead of or behind the remainder of the tree. The leaf buds are pointy and brown-coloured. The recent year's growth twigs are green and turn dark brown.  The flowers are in panicles of five to 10 together, yellow-green and without petals; flowering occurs in early spring after 30 to 55 growing degree days. The A. saccharum will generally begin flowering when it is between 10 and 15 years old. The fruit is a pair of samaras. The seeds are globose, 7mm to 10mm in diameter, the wing 20mm to 30mm long.  It is closely related to the “black maple”, which is sometimes included in this species, but sometimes separated as Acer nigrum. The western American “bigtooth maple” Acer grandidentatum is also treated as a variety or subspecies of “sugar maple” by some botanists.












































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