Alnus cremastogyne (Alder)
Michael's Opinion
Alder is the common name of a genus of flowering plants (Alnus) belonging to the birch family Betulaceae. The genus comprises about 30 species of monoecious trees and shrubs, a few reaching a very large size, distributed throughout the north temperate zone, with a few species extending into Central America and the northern Andes. The cremastogyne species is native to west China and mountainous areas in Asia. With a few exceptions, Alders are deciduous, and the leaves are alternate, simple, and serrated. The flowers are catkins with elongate male catkins on the same plant as shorter female catkins, often before leaves appear; they are mainly wind-pollinated, but also visited by bees to a small extent. These trees differ from the birches (Betula, the other genus in the family) in that the female catkins are woody and do not disintegrate at maturity, opening to release the seeds in a similar manner to many conifer cones. Alder is particularly noted for its important symbiotic relationship with a nitrogen-fixing bacterium, so Alder improves the fertility of the soil where it grows. As a pioneer species, it helps provide additional nitrogen for the successional species which follow.
Botanical Information
| Family | Betulaceae |
| Genus | Alnus |
| Species | cremastogyne |
| Category | Woody |
| Type | Tree (deciduous) |
| References | |
| Origin | South Western China and mountainous areas in Asia. |
| Ethnobotanical Uses Disclaimer | Alder is particularly noted for its important symbiotic relationship with a nitrogen-fixing bacterium. This bacterium is found in root nodules, which may be as large as a human fist, with many small lobes, and light brown in colour. The bacterium absorbs nitrogen from the air and makes it available to the tree. Alder, in turn, provides the bacterium with sugars, which it produces through photosynthesis. As a result of this mutually beneficial relationship, Alder improves the fertility of the soil where it grows, and as a pioneer species, it helps provide additional nitrogen for the successional species which follow. Alder bark contains the anti-inflammatory salicin, which is metabolized into salicylic acid in the body. Some Native American cultures use red Alder bark (Alnus rubra) to treat poison oak, insect bites, and skin irritations. Alder wood is appreciated for its claimed tight and even balanced tone, especially when compared to mahogany. |
Details
| USDA Hardiness Ref. | |
| Canadian Hardiness Zone | 4b - 6b |
| Canada Hardiness Ref. | |
| RHS Hardiness Ref. | |
| Temperature (°C) | -31 |
| Temperature (°F) | -25 |
| Height | 12 - 20 m. |
| Spread | 6 - 14 m |
| Flowering Period | May, June, July |
Description and Growing Information
| General Description | This species has been placed on the IUCN Red List as least concern. |
| ID Characteristic | The leaves are oval, oblong, and green, whereas the flowers are catkins, and the bark is smooth. |
| Pests | Butterflies feed on the nectar such as Blue coppers, and Neozephyrus helenae. |
| Habitat | Alder thrives in forests, mountains, slopes, and streambanks or rivers, at an altitude of 500 - 3000 m above sea level. |
| Bark/Stem Description | The plant's bark is grey or grey-brown with a smooth texture. |
| Flower/Leaf Bud Description | The bud is gritty, glabrous, and scaly; usually with 2 scales. It has a grey colour that will turn orange when the bud is fully mature. |
| Leaf Description | The leaves are green and somewhat rounded at their base. 8 - 10 lateral veins are situated on each side of the midvein. The petiole is about 1 - 2 cm, and if the plant is young, its color would be yellow. The leaf is glabrous , sometimes light yellow pubescent when young. The leaf blade is obovate obovate-oblong or oblong. The leaf is slender, with dimensions of 4 - 14 x 3.5 - 8 cm. |
| Flower Description | The Alder flowers are catkins with elongate male catkins on the same plant as shorter female catkins, often before leaves appear; they are mainly wind-pollinated. Catkins are elongated clusters of single-sex flowers bearing scaly bracts, and usually lacking petals. The flowers bloom in May and June. |
| Fruit Description | The stalks that the fruit grows on are about 4.4 - 5 cm long. The fruit is solitary, is an array of colours and is very gritty on the outside and looks almost like a pinecone. Fruit matures in August and September. The catkins of some alder species have a degree of edibility, and may be rich in protein. They have been reported to have a bitter and unpleasant taste, so they are more useful for survival purposes. |
| Colour Description | The fruit has an array of colours. |