Thursday, May 28, 2020

Erythrina x bidwillii-- One of my very favorite plants!

Seeing hummingbirds in my garden is one of my greatest thrills! Because of this, I have planted many hummingbird-attracting plants. Good thing I love the color red! One of favorite plants is also a hummingbird favorite, Erythrina x bidwillii. There are many Erythrina species to love and they are pantropical in distribution-- including both Old World and New World species. I found a very helpful web page describing this written by Wayne Armstrong of Palomar College. Old World species tend to have sturdy open flowers with amino acid-rich flowers for perching birds while many New World species target hummingbirds with more delicate slender flowers and sucrose-rich nectar especially suited to their high energy needs. This is very interesting to me since I have several New World species and selections in my garden. I had assumed that all New World Erythrinas fed hummingbirds, but I was wrong. I waited in anticipation for my Erythrina crista-galli to bloom, predicting increased hummingbird activity, only to find it is not their favorite tree. It turns out 55 of the 70 New World species are hummingbird pollinated. Erythrina crista-galli is mainly pollinated by passerines, and secondarily, by hummingbirds and bees. Unlike other strictly passerine-pollinated Erythrinas, this one has lower amino acid levels so appeals to a wider array of pollinators. Orioles and managers frequent passerine-oriented Erythrinas.
Erythrina crista-galli flowers                                                                                          S. Reeve                      

Erythrina x bidwillii flowers                                                                                          S. Reeve 

Notice how the flowers of the Erythrina crista-galli have the banner petal oriented like a dish so perching birds can grab the rim and sip nectar. The banner is also stout and sturdy and can support the weight of a small bird. The Erythrina x bidwillii has a long banner petal that is folded in the middle to form a tube and oriented downward because hummingbirds do not need any structure to support them as they feed. Fascinating, right?

Compared to my Erythrina crista-galli, Erythrina x bidwillii is crazy with pugnacious hummingbirds when it blooms. The rich red of the flowers is particularly satisfying to me. Flower wands as long as 3 feet cover this plant when it blooms. it is long-blooming starting in May and sending out more blooms throughout the summer. 

Erythrina x bidwillii                                                                  S. Reeve

                             Erythrina x bidwillii                                                                  S. Reeve

The blooms are not always so beautiful. Last year, after a particularly wet winter (for here anyway, lol) my tree had borers that destroyed most of the blooms. The culprit was most likely the Erythrina stem borer (Terastia meticulosalis). The ESB is a small, well-camouflaged brown moth that originated in Florida and has been seen in Southern California since 2015, In California, the ESB has been observed on E. × bidwillii, E. chiapasana, E. coralloides, E. crista-galli, and E. falcata--all New World species.

Before moving here I had the good fortune to grow E. x bidwillii in Athens, GA. This was a dieback shrub that would grow back in the heat of the summer, and get nipped back by frost in the fall. It is always a welcome addition to my garden. The plant is root hardy to USDA Zone 7b and is soil-type tolerant, as long as it is well-drained. I say this because I had acidic thick clay soil pH 5.3 in Athens and have neutral-to-slightly alkaline soil here in Calfornia, and it grows just fine in either place. It does best in full sun and looks best with regular water. I have seen it, though, blooming just fine with no summer water in San Diego. 

     Anna's Hummingbird standing guard                                                                                        S. Reeve

California native Anna's Hummingbirds, and Allen's Hummingbirds fight over this plant here in La Mesa, CA but in Athen's GA, we had the Ruby-throated Hummingbirds. One of the main reasons I moved here was for year-around hummingbirds! Between the many native hummingbird plants planted here and all of the other hummingbird plants I have planted, I see hummingbirds all of the time. I prefer to use plant flowers to feed them and it makes me happy to see them all over my garden!

You may have wondered about the "x" in the middle of the Erythrina x bidwillii? The letter signifies a cross between two species of Erythrina. In this case, the cross was made in between Erythrina herbacea a spring-blooming North American shrub that dies back in colder climates, and Erythrina crista-galli, a summer-blooming South American tree. They both possess the distinctive leaf arrangement of three leaves with the terminal leaf being largest. Erythrina crista-galli has spiny leaves and Erythrina herbacea has curving thorns on the stems. Erythrina bidwillii also has curving thorns, but they are not numerous. I prune the plant while wearing shorts and a short-sleeved shirt with no bodily damage.

            Maturing wand of flowers showing lengthening petals out of the calyx                           S. Reeve

As much as I love this plant one thing frustrates me about it, it has a rangy habit and does not attain the aesthetic ideal of how a small tree should look. Unlike, in zones lower than Zone 9 this plant is not a dieback shrub, but a small tree that does not dieback, and it maintains a woody trunk. In the spring this plant throws up abundant stems ending in long arching wands of flowers while blooming stems from last year are dead and show up distinctly as white curving skeleton bones the following year. To neaten the plant, these must be cut out. I normally do that in the spring, but I will try to cut them out in the fall this year. The wood of the plant is very light like balsa wood, and would easily float. Knowing what I know now about this plant in Zone 10b, I think it is worth the time and expense to buy a plant specifically trained as a tree, so there is an attractive structure to prune back to each year. Most Erythrina crista-galli are trained this way. 

If you love hummingbirds this is a great plant for your garden.

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