Desert Ironwood a keystone species

The delicate pea-like blossom

Two caonopies overlap in a dry wash

Early May is bloom time for the desert ironwoods and the low desert is scattered with these handsome natives cloaked in clouds of lavender blooms. The orchid-like flowers seem incongruous on so stalwart a tree, known for its extremely dense wood. The blooms are short lived and will be replaced by two inch pods, each containing several shiny brown seeds. These protein rich seeds are relished by verdins, cactus wrens, doves, quail and other birds as well as desert rodents and coyotes. Bighorn sheep and deer munch on seeds and browse the tiny leaves. The drooping branches of the ironwood tree create a shady retreat for coyotes and javalinas. An ironwood tree alone can create a cool and shady microclimate. The legume’s roots activate nitrogen in the soil providing nutrients for other plants as well. The rich soil and umbrella of dense protective branches make the desert ironwood an important nurse plant for tender seedlings of saguaro, night blooming cereus and organ pipe cactus. Many insects are attracted to the complex environment beneath and within the ironwood, which becomes a magnet for insect eating birds and reptiles. It is estimated that 160 species of plants and 80 species of birds have beneficial arrangements with the desert ironwood tree.
Ironwoods are found only in the Sonoran Desert, where they are among the largest and longest living plants; some surviving more than 800 years. Despite their longevity the trees do not germinate easily and have been wiped out in some areas because of overuse for firewood and carving. The wood is among the heaviest in the world and sinks in water. It burns hot and slow and provides excellent cooking coals. Due to innate toxicity the dead wood decomposes incredibly slowly and is considered nearly non-biodegradable. Ancient peoples used the desert ironwood for arrowheads and tool handles.

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