For today’s photographs of silk tree or mimosa tree, let’s start with an excerpt from the Vancouver Trees App, courtesy of Douglas Justice:
Albizia julibrissin is a small, exotic looking, fine-textured tree, native across southern Asia, from Turkey and the Caucasus in the west through the Himalayas and China, south to Japan and Indochina. Its primary value is in its summer effect: broadly spreading, slender alternately arranged branches produce delicate, twice-pinnately-compound leaves and silky, pink, powder-puff-like, late-summer flowers. During the growing season, the look is graceful, umbrella-like, and very tropical. In the evening, cold weather and the rain, the leaves neatly put themselves to bed, folding up elegantly until better conditions return.
This phenomenon, sometimes known as “night closure” is facilitated by leaf structures called pulvini, which are joint-like thickenings that occur along the leaf stems. Pulvini are common throughout the pea family (Fabaceae) and should not be confused with the woody pegs of Picea and Tsuga species that are also (confusingly) known as pulvini. In the winter, with its few, mostly unbranched stems, the silk tree is embarrassingly gaunt. Added to that, albizias are notorious for being among the last trees to leaf out and among the first to drop their leaves in autumn. For example, Vancouverites won’t see leaves emerge on a silk tree until the last week of May or first week of June, some six to eight weeks later than most other common deciduous trees.
Daniel adds: In parts of the southeastern USA, Albizia julibrissin is considered an invasive species. Douglas also notes in the Vancouver Trees app that the species has a preference for “dry winter conditions”; this is one of the reasons it can be grown locally without much concern.