, Australia
Erythrina crista-galli is a small tree, the girth of its trunk measuring . Normally it grows tall, although some individuals, such as in the Argentine provinces of
Salta,
Jujuy and
Tucumán, can grow up to . The woody trunk of the tree is equipped with irregular and
thorny branches and can reach 50 cm in circumference. The
root is a
taproot with
nodules produced by
nitrogen-fixing bacteria. The bacteria live in
symbiosis with the tree, facilitating the tree's absorption of nitrogen in return for organic substances which the bacteria need. The tree's trunk is woody with irregular, spiny branches. These branches form a layer without definite form and die after flowering.
Flowers and fruit ,
Argentina The red
flower, arranged in
inflorescences of the
raceme type, is pentameric, complete, and of bilateral symmetry. Its
calyx is
gamosepalous, like a little red thimble. The corolla, like that of other
legumes like
common beans, is butterfly-shaped; however, the largest petal, called the "standard", is arranged in the lower part. The two petals called "wings" are so small that they are practically hidden within the calyx. The remaining two petals partially fuse together on occasion and form the flower's keel or "carina"; this protects its reproductive organs. The
androecium consists of ten
stamens, one free and nine united by their filaments (gynostemial androecium). The unicarpel gynoecium is welded between the stamens like a knife in its sheath. The tree flowers in the summer, from October to April in their native South America and from April to October in the northern hemisphere. The flowers are rich in
nectar and are visited by
insects, which usually have to crawl underneath the carina and thus
pollinate the flowers. The tree's fruit is a
legume, a dry pod a few centimeters in length derived from a single
carpel and contains about 8–10 chestnut-brown bean-shaped seeds. The cotyledons are
hypogeal, staying underground upon germination. ==Cultivation==