Winter Solstice: Ferns and Mistletoe

December 21, 2008

We had frost last night but this afternoon was warm and sunny, so we hiked in a rocky, sand-filled wash in the Empire Mountains.  One shady north-facing outcrop, sheltered by now-leafless young soapberries and canyon hackberry trees, was covered in lichens and the gray-green fuzzy fronds of Cheilanthes eatonii, one of the more common desert ferns.  It made a wintry but colorful Solstice picture:

Winter Solstice - desert fern

Winter Solstice - desert fern

We found a big velvet ash tree hosting several clusters of mistletoe (Phoradendron flavescens) which usually grows on oaks but is also found on ash and hackberry. 
Phoradendron flavescens on Velvet Asn

Phoradendron flavescens on Velvet Ash

All mistletoe species are parasites but this one rarely kills desert trees as long as the trees have plenty of water.  This species is found on oaks in the Eastern U.S. and looks very similar to Viscum album, the Old World mistletoe of European mythology.  Both species have large rounded leaves and berries that are white when ripe.   Both plants are dark green in summer but fade to chartreuse or golden yellow in winter, which is why the Roman poet Vergil called mistletoe the “Golden Bough”.  Today, as I stand underneath the bare ash tree in the wash, the lacy, ball-shaped clusters of mistletoe have an Otherworldly glow on the Winter Solstice as they catch the last of the Old Sun’s light in late afternoon.
The most common desert mistletoe is Phoradendron californicum, which grows on legumes such as mesquite, ironwood, palo verde, and acacia.  Its stems are dark green all year, its leaves are reduced to tiny scales, and its berries are white, pink, or red when ripe.  It often kills palo verde trees, which are fast-growing, short-lived, and have very soft wood.  But the ironwood (Olneya tesota), famous for its slow growth and dense, heavy wood, can withstand thick infestations of mistletoe for many years.  This mistletoe grows in dense hanging clumps, creating ideal nesting sites for the phainopepla, which feeds on the sticky berries and disperses the seeds.  The plant I photographed today was growing on acacia, and the flaming berries held the last warmth of the desert sun:
Phoradendron californicum on Acacia

Phoradendron californicum on Acacia

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One Response to “Winter Solstice: Ferns and Mistletoe”

  1. judithornot said

    I love when you post about the plants there, Lorena. I had no idea about the different varieties of mistletoe. Happy Solstice!

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