Excerpts from Jim Conrad's
Naturalist Newsletter


from the July 7, 2013 Newsletter issued from the Frio Canyon Nature Education Center in the valley of the Dry Frio River in northern Uvalde County, southwestern Texas, on the southern border of the Edwards Plateau, USA

Back in Kentucky caladiums used to grow around my mother's house, and that was very nice. I don't recall those caladiums flowering, however, while here in southwest Texas my neighbor Phred's plants are very floriferous, as you can see above.

In Mexico we saw many plants with flower structures like the pale ones in that photo's upper left, for the plant family to which caladiums belong -- the Arum or Jack-in-the-pulpit Family, the Araceae -- is a large, important one in the moist tropics, and the structure shown in the above picture is very typical of that family. A close-up is shown below:

CALADIUM BICOLOR, flowering structure

In that picture we see many flowers. The banana-like item standing vertically and partly enveloped by the whitish hood is the "spadix," the Jack part of Jack-in-the-pulpit. The whitish hood, or "spathe," is the pulpit part. The spadix's grainy surface is formed by the flat tops of many closely packed anthers -- the pollen-producing, baglike tips of stamens of male flowers. Notice that below the white part of the spathe the spathe turns reddish and its edges curve, overlap one another, and the spathe bulges outward. If you force the bulging part open you'll find the base of the spadix clothed with numerous female flowers. Often in the Arum Family, once the female flowers are pollinated, the top male part of the spadix and the top, flaring part of the spathe wither away while the bulging lower part of the spathe expands and becomes a container protecting the lower part of the spadix on which ovaries of female flowers mature into fruits.

A garden columnist here in Texas advises snipping off caladium flowering structures because once the female flowers are pollinated the fruiting structures aren't pretty. I find them so interesting that I'd never do that. I don't see that their presence does any harm to the plant.

Of course I wondered what kind of caladium appears in my pictures. What I figured out was that the world of caladiums is enormous. Our plant is probably one of over a thousand named cultivars of the species CALADIUM BICOLOR, originally from Brazil and other parts of tropical America. You might enjoy browsing some of the hundreds of cultivars shown at http://www.classiccaladiumsllc.com/varieties/varieties.htm

Besides all those cultivars of the species bicolor, several other caladium species are known as well, and certain cultivars on the market carry genes from those other species. Sometimes the genetic history of certain cultivars is so complex that they are referred to as Caladium x hortulanum, the "x" indicating that the plant is a hybrid, and the hortulanum meaning that it's a horticultural creation.

As with many members of the Arum Family, all parts of caladium are poisonous, containing calcium oxalate crystals and the protein asparagine. Fortunately, having calcium oxalate crystals in the mouth is so painful that I doubt any creature, including a human, would eat enough to die. I know what pain these crystals produce because when I was a teenager I bit into a raw Jack-in-the-pulpit corm.

Of course it makes sense for members of this family to be so well armed with hurtful chemicals. Usually their leaves are so large and succulent that any herbivore not knowing about the calcium oxalate crystals would want to eat them. The first mouthful, however, should convince the herbivore henceforward to stay away.