Many northern California folks migrate to the desert during the winter holidays, to enjoy them in the warmth and beautiful landscapes of the Mojave and Sonoran deserts. There too you can find mistletoe, the plant of Christmas kisses. Desert mistletoe, Phoradendron californicum Nutt., a member of the sandalwood family Santalaceae, is, however, quite unlike the familiar congeneric broad-leaved, white-berried mistletoes that one sees everywhere in Solano County. In my opinion, desert mistletoe's translucent salmon-colored berries win the beauty contest hands down. I must admit, though, that those lovely berries come nestled in a spiky package and are produced on an odd plant that many find unattractive.
The jointed stems of P. californicum form dense clumps up to a yard long inside several species of thorny desert trees belonging to the legume family Fabaceae, such as mesquite (Prosopis spp.), palo verde (Parkinsonia spp.), and desert ironwood (Olneya tesota A. Gray). Rootlike structures called haustoria attach the mistletoe to a tree branch and extract nutrients and water from the host, but the green mistletoe branches are photosynthetic, making mistletoe a “hemiparasite.” The jointed branches look leafless and lumpy because the leaves are reduced to scales and flowers and berries are produced on short, protruding stems. The tiny, fragrant, petal-less flowers produce berries soon after winter bloom.
Those berries are relished by many kinds of wildlife, most especially by a handsome bird for which desert mistletoe berries are a key food source: the Phainopepla, Phainopepla nitens (Swainson), the most northerly representative of the mainly tropical Central American silky flycatcher family, Ptiliogonatidae. This is a crested bird with a short, slender bill, a long tail, and striking red eyes, slightly bigger than a sparrow. Males are blue-black, with white wing patches that flash when they fly. Females are uniformly grayish-brown. They sometimes nest within the mistletoe clump itself. Although it is most common in desert washes, this bird ranges northward to north-central Californian oak foothills (the photo was taken at Lake Solano).
The Phainopepla is one of the creatures most responsible for spreading desert mistletoe, by wiping the sticky seeds off of their feet and beaks onto neighboring branches or other trees. They also deposit viable seeds onto new host trees in their droppings. Although mistletoe, which can live for 60-70 years, weakens host trees, it rarely kills them. If hosts succumb under unusual pressure from an exceedingly dense mistletoe infestation, drought, disease, or heavy insect attack, the mistletoe dies along with them.
Selected references
Buscher, L. & D. Desert Mistletoe: Photos of ‘Tree Thieves' in the American Southwest. Live Science, published 12/18/2014, https://www.livescience.com/49145-desert-mistletoe-photos.html. Viewed 7/17/23.
Ledger, D. 2016. California Native Plant Society: Everything You Wanted to Know About Mistletoe. Record Searchlight, Redding, CA, published June 3. california-native-plant-society-everything-you-wanted-to-know-about-mistletoe (redding.com), viewed 12/9/23.
The Cornell Lab, All About Birds: Phainopepla, Phainopepla Overview, All About Birds, Cornell Lab of Ornithology. Viewed 12/9/23.
Wikipedia, Phoradendron californicum, https://en.wikipedia.org/wiki/Phoradendron_californicum, viewed 7/17/23, and Phainopepla, Phainopepla - Wikipedia, viewed 12/9/23.