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Acorns from the Sawtooth oak tree or kunugi tree. Quercus acutissima. The tree is dense, has a pyramidal in youth; and has a broad to rounded shape with wide spreading branches as it grows older. It has rigid furrowed bark. It has leaves that are 3.5 to 7.5″ alternate, and that are simple, lustrous dark green. Its leaves turn yellow to golden brown in the fall, but the leaves persist into winter. It has golden male catkins; .7″ acorn. More info here.

 

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NATURE IN SHORT / Japan’s many species of acorn trees make identification challenging

Kevin Short / Special to The Daily Yomiuri

I grew up thinking of oaks as the noblest of trees, richly endowed with qualities such as “mighty,” “solid” and “dependable.” I also grew up thinking of the acorn and the oak as a metaphor for patiently building something huge and wonderful from a small, humble beginning.

Oaks, classified in the genus Quercus, are among the most common and familiar trees throughout the Northern Hemisphere temperate zones, with around 500 to 600 species identified worldwide. Together with beech, chestnut, tanoak and chinkapin, they form the Fagaceae, or beech family. Both tanoaks and chinkapins, with 300 and 100 species each, also produce acorns, giving a grand total of nearly 1,000 species of acorn trees! The outstanding characteristic of the beech family is the hard nut, which is encased in a protective covering known as a cupule. The cupule surrounds and protects the nut in its delicate growing stage. When the nut matures it outgrows the cupule, as in acorns, or the cupule splits open to release the nut, such as in chestnuts and beechnuts.

Acorns are ubiquitous here in Japan. Oaks form a major component of native forests throughout the land. The ubame-gashi (Quercus phillyraeoides) for example, grows right on the seacoasts, while a hardy variety of the mizunara (Q. crispula), thrives high in the subalpine zone, right up to the very edge of the timberline. The Okinawa urajirogashi (Q. miyagii) is a common tree in the subtropical forests of southern Okinawa Prefecture; while the kashiwa (Q. dentata) mixes it up with spruce and fir in the subarctic woodlands of Hokkaido.

Before coming to Japan, my image of an oak was a wide-spreading tree with small, deeply lobed leaves that turn red and yellow in autumn. Here in Japan, however, there are oaks with huge leaves and oaks with entire leaves (that is, smooth-edged leaves without any lobes or teeth at all). Also, some Japanese oaks do turn color and the leaves drop off in late autumn, but there are also many species that keep their leaves all year round.

Look for Japanese acorns wherever you see a substantial forest. When collecting acorns, try to find some with the cupule still attached, or collect some cupules from the ground as well. Also be sure to collect some typical leaves from the tree, and if possible, to take a picture of the trunk. Japan is home to 15 or 16 species of true oak, plus two species each of tanoak (genus Lithocarpus) and chinkapin (genus Castanospis) that also produce acorns. Trying to determine an acorn’s species is a great challenge. To begin with, check the cupule. There are four basic types; burred, scaled, ringed and sheathed.

The burred acorns, with only three species, all deciduous forest trees, are pretty easy to work with. The kashiwa (Q. dentata) has deep lobes on the leaf, while the two species with lanceolate (long, thin) leaves and sharp spines can be told apart by checking the color on the underside of the leaf, green in the kunugi (Q. acutissima) and with a whitish tint in the abemaki (Q. variabilis).

The scaled acorns are a bit more complicated. There are three species with lobed leaves, all deciduous forest trees. These require a close look at the size of the leaf and the length of the leaf stalk. The stalk of the mizunara (Q. crispula) is either very short or totally lacking; while the konara (Q. serrata) has a conspicuously longer stalk. The konara is usually found in lowland forests, and the mizunara higher up on the mountainsides, but there are some areas where their ranges overlap. The nara-gashiwa (Q. aliena) is an uncommon species with a fairly long stalk, but with leaves much larger than the other two species.

The ubame-gashi is an evergreen coastal species with a scaled acorn. The oval leaves are small, with distinct teeth on the margin. The mateba-jii tanoak (L. edulis) also has a scaled acorn. This species grows wild in Kyushu, but is planted widely in parks and along streets, and also in plantations on the Boso and Miura peninsulas. Its acorn is among the largest found here in Japan. There is actually one more species of tanoak, shiribuka-gashi (L. glabra), but I have never been able to find or identify it.

The ringed acorns, all evergreen forest trees, form by far and away the most difficult group. You have to carefully check the edge of the leaf for teeth or bumps, and also turn the leaf over to inspect the underside for color. Only one of these, the aka-gashi (Q. acuta) has entire leaf margins. The rest have varied size and number of teeth, though none of them are lobed like the deciduous species. The urajiro-gashi (Q. salicina) and Okinawa urajirogashi both show a distinctive white tint on the underside of the leaf, but the latter sports enormous (four centimeters long) acorns more than twice the size of the former.

The sheathed acorns belong to one of two species of chinkapin. The sudajii (C. sieboldii) has oval acorns and a deeply furrowed trunk; while the tsuburajii (C. cuspidata) has rounder acorns and a smooth trunk.

(Oct. 16, 2006) 

NATURE IN SHORT / Japan’s many species of acorn trees make identification challenging

Kevin Short / Special to The Daily Yomiuri

I grew up thinking of oaks as the noblest of trees, richly endowed with qualities such as “mighty,” “solid” and “dependable.” I also grew up thinking of the acorn and the oak as a metaphor for patiently building something huge and wonderful from a small, humble beginning.

Oaks, classified in the genus Quercus, are among the most common and familiar trees throughout the Northern Hemisphere temperate zones, with around 500 to 600 species identified worldwide. Together with beech, chestnut, tanoak and chinkapin, they form the Fagaceae, or beech family. Both tanoaks and chinkapins, with 300 and 100 species each, also produce acorns, giving a grand total of nearly 1,000 species of acorn trees! The outstanding characteristic of the beech family is the hard nut, which is encased in a protective covering known as a cupule. The cupule surrounds and protects the nut in its delicate growing stage. When the nut matures it outgrows the cupule, as in acorns, or the cupule splits open to release the nut, such as in chestnuts and beechnuts.

Acorns are ubiquitous here in Japan. Oaks form a major component of native forests throughout the land. The ubame-gashi (Quercus phillyraeoides) for example, grows right on the seacoasts, while a hardy variety of the mizunara (Q. crispula), thrives high in the subalpine zone, right up to the very edge of the timberline. The Okinawa urajirogashi (Q. miyagii) is a common tree in the subtropical forests of southern Okinawa Prefecture; while the kashiwa (Q. dentata) mixes it up with spruce and fir in the subarctic woodlands of Hokkaido.

Before coming to Japan, my image of an oak was a wide-spreading tree with small, deeply lobed leaves that turn red and yellow in autumn. Here in Japan, however, there are oaks with huge leaves and oaks with entire leaves (that is, smooth-edged leaves without any lobes or teeth at all). Also, some Japanese oaks do turn color and the leaves drop off in late autumn, but there are also many species that keep their leaves all year round.

Look for Japanese acorns wherever you see a substantial forest. When collecting acorns, try to find some with the cupule still attached, or collect some cupules from the ground as well. Also be sure to collect some typical leaves from the tree, and if possible, to take a picture of the trunk. Japan is home to 15 or 16 species of true oak, plus two species each of tanoak (genus Lithocarpus) and chinkapin (genus Castanospis) that also produce acorns. Trying to determine an acorn’s species is a great challenge. To begin with, check the cupule. There are four basic types; burred, scaled, ringed and sheathed.

The burred acorns, with only three species, all deciduous forest trees, are pretty easy to work with. The kashiwa (Q. dentata) has deep lobes on the leaf, while the two species with lanceolate (long, thin) leaves and sharp spines can be told apart by checking the color on the underside of the leaf, green in the kunugi (Q. acutissima) and with a whitish tint in the abemaki (Q. variabilis).

The scaled acorns are a bit more complicated. There are three species with lobed leaves, all deciduous forest trees. These require a close look at the size of the leaf and the length of the leaf stalk. The stalk of the mizunara (Q. crispula) is either very short or totally lacking; while the konara (Q. serrata) has a conspicuously longer stalk. The konara is usually found in lowland forests, and the mizunara higher up on the mountainsides, but there are some areas where their ranges overlap. The nara-gashiwa (Q. aliena) is an uncommon species with a fairly long stalk, but with leaves much larger than the other two species.

The ubame-gashi is an evergreen coastal species with a scaled acorn. The oval leaves are small, with distinct teeth on the margin. The mateba-jii tanoak (L. edulis) also has a scaled acorn. This species grows wild in Kyushu, but is planted widely in parks and along streets, and also in plantations on the Boso and Miura peninsulas. Its acorn is among the largest found here in Japan. There is actually one more species of tanoak, shiribuka-gashi (L. glabra), but I have never been able to find or identify it.

The ringed acorns, all evergreen forest trees, form by far and away the most difficult group. You have to carefully check the edge of the leaf for teeth or bumps, and also turn the leaf over to inspect the underside for color. Only one of these, the aka-gashi (Q. acuta) has entire leaf margins. The rest have varied size and number of teeth, though none of them are lobed like the deciduous species. The urajiro-gashi (Q. salicina) and Okinawa urajirogashi both show a distinctive white tint on the underside of the leaf, but the latter sports enormous (four centimeters long) acorns more than twice the size of the former.

The sheathed acorns belong to one of two species of chinkapin. The sudajii (C. sieboldii) has oval acorns and a deeply furrowed trunk; while the tsuburajii (C. cuspidata) has rounder acorns and a smooth trunk.

(Oct. 16, 2006)
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