TREES, PLEASE: “Silky” Trees

Floss Silk Flower with bee.

By Robin Y Rivet.

Valentine’s Day is nigh. Do you wish for romantic gifts of silken fabric, sweet fruit or gorgeous flowers? A genuine “silk” tree could be a gardener’s gift, but which one to choose? Many lovely species are called silk trees.

Silkworm caterpillars thrive by eating the foliage of Morus alba - a large-scale, white mulberry. Revered in Asia for thousands of years, these “silk trees” provide foliar food for larva that spin a strong, single strand that is woven into exquisite silk fabric, although millions of silk moth larvae perish during the refining process. Instead you might choose Morus nigra because the taste of the fruit is considered superior for humans, not larva or moths. A delicious Persian-type mulberry tree, ‘Black Beauty’ is available through mail order – its huge, sweet, sub-acid fruit tastes similar to a blackberry, and this tree’s stature matures at less than 15 feet.

Albizia julibrissin is also called a “silk tree” or sometimes “mimosa”, but only because its rosy-pink flowers have a resemblance to silky thread. You’ll really need to love this inflorescence, as it will fall to the ground in a romantic pink carpet, or become a messy, slippery pile of debris - depending on your mindset. If a fleeting mass of rosy-colored soil covering appeals to you, you’ll certainly relish the bounty of hummingbirds, bees and butterflies that home in on this silk tree’s prolific, scented flowers.

Albizia julibrissin – silk tree flowers.

The Australian silk oak’s Latin name Grevillea robusta is apt due to its rugged appearance, but it is neither an oak - nor particularly silky. Its taxonomy shows a relationship to trendy protea and grevillea flowering shrubs, as well the edible macadamia. Silk oaks are fast-growing (almost rank) trees, but their feathery, shimmery foliage has silvery-smooth undersides, and its profuse, spring flowers are golden-orange, attracting numerous birds and bees.

Floss Silk Tree.

The Chorisia genus was renamed Ceiba, and amongst Ceiba speciosa trees there is great variability between cultivars, but few nurseries seem to distinguish them. However, the Los Angeles Arboretum grows numerous types that bloom sequentially. In early autumn you’ll see ‘September Splendor’, then ‘Lasca Beauty’ and ‘Los Angeles Beautiful’, and finally around the new year, ‘Arcadia’ will bloom. In San Diego, floss silk trees can flower nearly any month of the year, so I suspect this is tied to genetic variation from chance seedlings. Most specimens have spiny-armored trunks, and large, pinkish or wine-red orchid-shaped blooms with mottled white or yellowish centers. A frost-tender relative, Ceiba pentandra is the source of kapok, a stuffing material once used for life-jackets and pillows. All floss silk trees have extraordinarily beautiful flowers, and I’ve seen resident birds collect the plant-based “silky fibers” that emerge from our silk tree’s large seedpods to use for local nesting materials. It’s hard to find, but the grafted ‘Majestic Beauty’ lacks the seriously spiny trunk, however love seldom arrives without some thorns…

Member Robin Rivet is an ISA Certified Arborist – contact her:


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