Juglans major
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Juglans major |
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| ( Torr. ) A. Heller |
Juglans major is a North American tree of the genus walnuts ( Juglans ).
features
Juglans major is a 5 to 18 m tall tree and sometimes forms several trunks. The bark is light to medium gray and divided into small plates like a checkerboard. The pith of the branches is brown. The terminal buds are narrowly ovate or conical, flattened and 4 to 7 mm long.
The leaves are 18 to 38 cm long, the petiole 3 to 6 cm. The 9 to 15 leaflets are lanceolate to lanceolate egg-shaped, symmetrical or sickle-shaped, 6.5 to 10.5 cm long and 1.5 to 3.4 cm wide. The leaf margin is serrated, the leaf tip narrowly pointed. The underside of the leaf is covered with head-like, glandular hairs, with simple or two- to four-pointed tufted hairs and often with scattered scales. There are often tufts of hair in the nerve axils. Head-like and glandular hairs sit on the upper side of the leaf, sometimes scattered tufts of hair, the upper side later becomes bald. The terminal leaflet is usually small or absent entirely.
The male kittens are 5 to 8 cm long. Each flower has 20 to 40 stamens . The pollen sacs are 1.2 to 1.4 mm long.
One to three fruits are formed per fruit cluster, which are approximately spherical or briefly ovoid and 2 to 3.5 cm in size. The surface is smooth and densely covered with glandular hairs and shield-shaped scales. The nuts are spherical to ovoid, 1.8 to 2.7 cm in size, deeply grooved lengthways. The surface between the furrows is smooth.
The number of chromosomes is 2n = 32.
distribution
Juglans major is native to the southern United States and Mexico. The trees grow on rivers and on rocky canyons at 300 to 2100 m above sea level.
Systematics
Juglans major is placed within the genus Juglans in the section Rhysocaryon . It is closely related to Juglans nigra and Juglans microcarpa .
Two varieties are distinguished within the species :
- Juglans major var. Major is the nominate form with the characteristics described above.
- Juglans major var. Glabrata W.E. Manning : The leaves are larger, less hairy, the fruit and nut are larger. It replaces the nominate form in the south, from around the 25th parallel.
supporting documents
- Donald E. Stone: Juglandaceae . In: Flora of North America , Volume 3. (online)
- Wayne E. Manning: The Genus Juglans in Mexico and Central America . Journal of the Arnold Arboretum, Volume 38, 1957, pp. 121-150.
Individual evidence
- ↑ Juglans major at Tropicos.org. In: IPCN Chromosome Reports . Missouri Botanical Garden, St. Louis
- ↑ Alice M. Stanford, Rachel Harden, Clifford R. Parks: Phylogeny and biogeography of Juglans (Juglandaceae) based on matK and ITS sequence data . American Journal of Botany, Volume 87, 2000, pp. 872-882.
