Water Willow

There’s something refreshing about seeing all these green, grassy-looking plants growing right in the Potomac River every summer. They aren’t grasses, though; they’re water willow (Justicia americana; Acanthaceae), an emergent aquatic whose rhizomes form vast stands of plants in the shallow waters of ponds and streams.

The plants will grow to as much as three feet tall, sending up long stems with tight clusters of flowers on the ends. Only a few stems at a time will bear flowers, but the blooming period of a colony can last two months or more.

 

Water willow is native to eastern North America, ranging from Texas and the eastern Great Plains northeastward to New York, Ontario, and Quebec. It’s endangered in Iowa and threatened in Michigan.

 

 

Of the roughly dozen and a half species of Justicia found in North America, this one is by far the most northern species. One other occurs in the southern part of the Mid-Atlantic, and one in the Mid-West; the rest seem to be found only in Florida, Texas, or the Southwest.

Last spring I found the closely related Justicia californica in Anza-Borrego Desert State Park, which grows as a shrub or tree in the Sonoran and Mojave Deserts.

Hard to believe they’re in the same genus.

Desert Shrubs and “Trees”

There are so many interesting plants in the desert, and not just forbs. In mid March when I was at Anza-Borrego, shrubs were in full bloom, too, and one really unusual tree-like plant was just starting. And then there were the palms.

Encelia farinosa

This shrub goes by the common names brittlebush, incienso, and gold hills. I saw them all over the place, standing like good omens, saying “welcome to Anza-Borrego!” with their cheery yellow flowers. Brittlebush is in the Asteraceae, of course, and can be found on hillsides and slopes in the Sonoran and Mojave deserts, at elevations from below sea level to 3,000 feet above or more, depending on which authority you consult.

Justicia californica

Known commonly as beloperone, chuparosa, and hummingbird bush, this species is found mostly in the Sonoran Desert, with a few occurrences in the Mojave. It can grow to six feet tall and twelve feet wide. Justicia, a genus in the Acanthaceae, has over 600 species, only a few of which are found in North America. Of those, the most widespread is Justicia americana, which ranges from Texas to Quebec; there are vast stands of it in the Potomac River every summer.

Fouquieria splendens

Ocotillo is such an unusual plant, it deserves a post all its own, but I’m short on time. Each stem can grow to 20′ tall, and a mature plant can have dozens of stems. They bear leaves only after sufficient rain. The bright red flowers attract hummingbirds.

From a distance you might think they’re a type of cactus, but they aren’t even closely related. (Going up on the taxonomic tree, cacti are in the order Caryophyllales, while ocotillo is in the Ericales.) There are only eleven species in the genus Fouquieria, which is the only genus in the family Fouquieriaceae. Ocotillo grows on slopes and hillsides, ranging from the southern Mojave through the Sonoran and Chihuahuan deserts.

Speaking of hummingbirds, while I was shooting some low-growing plant or other I heard this loud buzzing, and looked up to see this —>
That’s a black-chinned hummingbird, Archilochus alexandri. Once more I was both thankful to have a zoom lens, and wishing I had a longer zoom lens.

One of the greatest wildflower displays in Anza-Borrego was along the Borrego Palm Canyon trail, a nice, easy hike up a gentle grade that leads to actual running water and a big group of Washingtonia filifera, California fan palm. This plant in the Arecaceae can reach heights of 60 feet in the presence of open water. Click on the picture to see it larger; note the people on the boulder for scale, and how the brittlebush and chuparosa are growing together. California fan palm is native to the Sonoran and Mojave deserts, and is the only palm native to western North America.

Flower of the Day: Water-Willow

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aka American water-willow
Justicia americana
Acanthaceae

As spring turns into summer and the water levels in the Potomac drop, the stems and foliage of this aquatic plant appear along the river’s edge, growing out of the water.

20150616-20150616-_DSC0101 Water willow spreads by rhizomes, forming large colonies that help stabilize shorelines and provide habitat for small invertebrates.  Many types of bees, flies, and butterflies feed on the nectar or pollen.  I don’t know if water-willow could properly be considered a keystone species, but it certainly is ecologically important.

Hundreds of species of Justicia grow in tropical and temperate zones of the Americas and parts of Asia and Africa, but only about two dozen are native to the US.  American water-willow is by far the northernmost growing of these species, and can be found as far north as Ontario and Quebec, though no further west than Texas.  It’s threatened in Michigan and endangered in Iowa.

Although each flower is relatively short-lived, and only a few are produced at a time, the overall blooming period of the plant can be several months long.

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evening clouds reflected in the Potomac