By Robin Y Rivet.
Contrary to what easterners believe, winter in our mild region renders many tree species naked for months, and regional tree devotees often find it difficult to identify them when they’re deciduous. However, there’s plenty of clues that linger for a willing sleuth.
Approaches for dormant tree identification include scrutinizing bare branches for clinging dried foliage, fruits or pods; noting bud scars, bark texture, the size, shape and scale of the silhouette; or whether the tree has opposite or alternate branching. My favorite tip is snooping under the canopy for fallen, but still intact leaves; or finding seed capsules, legume fragments, dried flower pieces or even tiny seeds or berries. These might be hidden under mulch, or even buried in very shallow soil - but all are potential identification tools. Since they’re detached, you do need to be vigilant, and take note of possible adjacent wind-blown tree litter.
Surprisingly naturalized in our inland regions - especially near riparian spaces, is Carya illinoinensis. The pecan tree retains four-sided husks which split open and remain attached on defoliated limbs, long after the edible pecan nut pops out, and their distinctive compound leaves have blown away. Visually, these are so characteristic, you can identify an unclothed pecan from afar. This is also true for other nuts, like walnuts or almonds.
Coral-pink papery fruits on Koelreuteria spp. trees are typically mistaken for flowers, but these unique capsules desiccate and linger through winter, clustered on naked branches. Crape myrtle - Lagerstroemia spp. similarly retains capsules, although they sport vibrant red and orange fall foliage, defying the notion that SoCal lacks autumn interest. And don’t forget, crape myrtle bark is amazingly colorful all year. All are good clues for winter tree identification.
Tipu trees are native to the southern hemisphere, and therefore typically go dormant during spring instead of fall. Flowering in late summer, they develop a seed encased in what’s called a “samara”, that catches the wind like a helicopter, spinning away from the mother tree for promising landing spots. Other common species with samara-type seeds include Japanese maple, evergreen elm, California ash, Ailanthus, and Liriodendron tulipifera - the North American tulip tree. Like the tipu, the jacaranda is another southern hemisphere import, but it has an unmistakably large, irregularly-rounded seed capsule, with numerous seeds held within.
Most leguminous trees retain bean-like pods of varying length and girth, long after their characteristic foliage has thinned or vanished. Once you become familiar with the seed pods of acacia, carob, mimosa, palo verde, cassia, mesquite, and desert willow, you’ll soon find it amazing how easy it is to distinguish between them, although acacias species can be as challenging as eucalypts.
Eucalyptus and their related genera present some of the most interesting and diverse tree parts to decipher, especially since they’re difficult to identify from foliage, even if evergreen. Eucalyptus, Corymbia, Lophostemon, and Angophora all appear vaguely similar, until you closely examine their distinctly variable capsules and attachments. If you get stumped, EUCLID is one of the coolest Australian dichotomous keys available.
Once you sight seeds and cite their identification; you can now plant those seeds and make some more trees!