Comandra umbellata / bastard toadflax

Adjectives: clonal, drought tolerant, exposed, hemiparasite, interesting bits, native

Also known as: common comandra

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First of all, the origin of the common name, bastard toadflax, is boring, arising from the equally boring resemblance of the leaves to those of various toadflax species, including the noxious weed, yellow toadflax.

Other than that, the plant itself is fairly nondescript with teeny yellow/white, waxy flowers. It has, however, more oddities and interesting bits than most plants thousands of times bigger. A widely distributed species, bastard toadflax is found in all states and Canadian provinces, except (for some reason) Louisiana and Florida. My guess is that they just have insufficient testing and reporting in place. It is also found in the Mediterranean region, a phenomenon known as “disjunct distribution”. It is considered native on both sides of the Atlantic.

Still, this species is significant in that it is the only one in its genus, i.e. it is a monotypic genus. That could mean it is weird in some way or that systematists just haven’t gotten around to changing it. On the other hand, this classification has been unchanged for more than 200 years.

All that aside, Comandra is a perennial, rather short herb… no more than about a foot or two tall. The leaves, up to 1-1/2 inches long, are alternately arranged, although it is unlikely that this will ever attract your attention without the flowers. The stem leaves are somewhat succulent, longer than wide, and pointy, and they extend well up the stem, even just below the flower. The basal leaves are more oval.

Bastard toadflax forms colonies – clones – arising from thick, woody rhizomes. Some of these colonies can be very large (10s of square feet). The fibrous roots, rather than just absorbing nutrient and water like respectable plants, send out underground suckers (haustoria) that glom on to the roots of other plants (see “Interesting bits”).

The flowers are interesting in that they lack petals, despite what it looks like in the photos here. Instead, they have 5 greenish-white sepals that look like petals fused into a shallow bell. They are very small (about 1/4 inch across). The flowers are perfect (containing both male and female structures), and are insect pollinated. The range of insects interested in the pollen and nectar is wide, including various species of flies, bees, beetles and butterflies. The inflorescence is “hemispheric” – sometimes called a cyme, sometimes a corymb, sometimes an umbel. Whatever. In any case, it is a cluster of flowers at the top of a stem, arranged with different length pedicels so that they are spread out rather than opening one above the other.

The fruits, drupes (like cherries) are also very small but edible and sweet when unripe (so they say). In any case, small rodents like them.

Given its broad distribution, the one thing that characterizes its habitat is that it is usually found on dry, rocky sites. However, it is also sometimes found in woodlands and on roadsides.

Interesting bits – Continuing with the unusual aspects of the species, C. umbellata is hemiparasitic; it parasitizes over 200 known plant species of all shapes, sizes and life histories and from many different plant families, but it still has green leaves and does photosynthesis. In fact, all members of the family, the Santalaceae appear to be hemiparasitic. The Santalaceae is the sandalwood family and includes a hemiparasitic tree, Santalum album, a native of India, parts of Asia, and Australia … the source of that fine smelling sandalwood oil.

Bastard toadflax is also the primary host for a rust fungus, the comandra blister rust (Cronartium comandrae). The alternate host for this is various pine species. Compare this to the Puccinia monica fungus that affects Boechera spp. and you will find some interesting differences in life cycle. For one, Puccina colonizes Boechera as the alternate host rather than the primary host. For more on this and what rust fungi are, see the entry on Boechera pauciflora and the discussion essay, On pseudoflowers and parasites.