Juglans microcarpa
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Juglans microcarpa |
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| Berland. |
Juglans microcarpa is a North American plant species of the genus walnuts ( Juglans ).
features
Juglans microcarpa is a shrub or small tree up to 10 m in height. The bark is medium gray and rather heavily furrowed. The branches are notched with the distal edge of the leaf scar in which they stand. They are bald or bordered by a poorly defined area of velvet hair. The pith is light to dark brown. The terminal buds are spherical to briefly ovate, not flattened and 3 to 5 mm long.
The leaves are imparipinnate and 12 to 29 cm long, the petiole 1 to 3 cm. The 17 to 25 leaflets are lanceolate or narrowly lanceolate and slightly to strongly sickle-shaped. They are 5.2 to 6.3 cm long and 0.8 to 1.1 cm wide, the leaf margin is whole or serrated, the end of the leaf is long and pointed. The underside has head-like, glandular hairs, often with scattered scales. The axils of the nerves near the leaf base are usually, but not always, provided with a distinct tuft of hair. The top is covered with head-like, glandular hair. The terminal leaflet is usually small.
The male catkins are 3 to 7 cm long and have 20 to 25, rarely 35, stamens per flower . The pollen sacs are 0.8 to 1 mm long. Flowering time is spring (March to April, rarely until June).
The one to three fruits per fruit cluster are spherical, 1.4 to 2.3 cm in size, smooth and covered with glandular hairs. The nuts are spherical to compressed, 1.1 to 1.7 cm in size, grooved and smooth between the grooves.
distribution
Juglan's microcarpa is native to the US states of Kansas , New Mexico , Oklahoma and Texas as well as the Mexican states of Chihuahua , Coahuila and Nuevo León . It grows on streams and rivers from 200 to 2000 m above sea level.
Systematics
Juglans microcarpa is placed within the genus Juglans in the section Rhysocaryon . It is closely related to Juglans nigra .
Specimens with large leaflets (up to 9.6 cm long) could have been caused by introgression of Juglans major . They are sometimes considered as a separate variety ( Juglans microcarpa var. Stewartii (IM Johnston) WE Manning ) and are only known from Mexico. There are also known intermediate forms between Juglans microcarpa and Juglans nigra .
supporting documents
- Donald E. Stone: Juglandaceae . In: Flora of North America , Volume 3. (online, English)