Elephant's foot is an unusual member of the aster/daisy/sunflower family. Instead of having the usual composite flowerheads, it has doubly compound flowerheads: flowerhead-like clusters of flowerheads! It's a common late-summer and fall wildflower.
At a glance, elephant's foot is a much-forked, stout, shrublike nonwoody plant, usually about knee-high, that bears flat clusters of light lavender to white flowers.
The flower clusters are worth examining closely; each cluster is essentially doubly compound. What looks like a single floret in the cluster is actually a small flowerhead of 4 florets. This arrangement makes genus Elephantopus an unusual member of the sunflower family:
- The basic units of the flowerheads are disk florets, whose light lavender to white petals are joined at their bases into a tube; the tube's 5 petal lobes flare outward. (Similar to ironweeds, the flowerheads contain no true strap-shaped ray florets such as the yellow ray florets of sunflowers.)
- There are usually 4 florets per flowerhead, and each flowerhead is subtended by its own ring of green, leafy, often lance-shaped and hairy bracts. It can be hard to distinguish the individual flowerheads unless you pick apart the flower cluster.
- Then, at the tips of the plant's branches, 3 to 20 flowerheads are crowded together into headlike clusters; these clusters are subtended by 3 leaflike bracts, which can be about 1 inch long.
Blooms August–October.
The leaves are scattered along the stems; they are alternate, oval, obliquely toothed, the lower ones narrowed rather abruptly at the base, the upper ones normally sessile (stalkless) and quite small. The leaves are sparsely soft-haired to moderately coarse-haired above and below. At flowering time, the leaves are mostly along the stem, as opposed to mostly at the base. Basal leaves are sometimes absent at flowering time.
Similar species: The foliage and habit of this plant are very similar to the closely related ironweeds (Vernonia), but the double-compound flowerheads of elephant's foot make it instantly recognizable. Ironweeds have separate flowerheads that are not grouped into such secondary clusters. Also, although ironweeds occasionally produce whitish flowers, they are typically bright magenta or purple.
For a few more elephant's foot species that might possibly be discovered in our southernmost counties, see Ecosystem Connections.
Height: to 3 feet.
Scattered, mostly along and south of the Missouri River.
Habitat and Conservation
Occurs in wooded valleys, lowlands, openings in woods, banks of streams and rivers, pastures, and roadsides.
Status
Native Missouri wildflower.
Human Connections
This drought-tolerant plant can be used in native plant gardens, prairies, and woodland gardens. It has showy flowers and reportedly grows well in relatively dry and sandy soils. If you mass the plants, the large lower leaves early in the season make it a good groundcover.
Members of this genus have been explored for possible medicinal usage.
Whence the weird name? Although the lowest leaves of this species, prior to bloom time, can be quite large, the name “elephant’s foot” apparently came from tropical members in the same genus, which do have bottom leaves large enough to suggest the feet of elephants.
In their labs, students in beginning botany classes learn how to identify plants using technical descriptions, and this often involves seeing details of flowers and fruits. At first it seems rude to dissect a flower with knives and needles, but it's a great way to see the structures. Pick apart an elephant's foot flower cluster, and then do the same to a thoroughwort or ironweed. You'll see structural similarities and startling differences!
Ecosystem Connections
Late-blooming wildflowers like this provide nectar for pollinating insects, including many butterflies, wasps, beetles, and bees, that are active in late summer and early fall.
Several types of insects feed on elephant's foot, and these in turn become food for other animals ranging from spiders, robber flies, and assassin bugs to fish, amphibians, reptiles, mammals, and birds. Some insects that feed on elephant's foot include
- some species of tumbling flower beetles, whose larvae bore into the stems
- aphids in genus Uroleucon, which suck the juices of plants, especially those in the sunflower family
- the larvae of a tiny moth called Cremastobombycia ignota. The caterpillars of this moth are leaf miners that chew squiggly tunnels within the leaves of several members of the sunflower family.
The multitude of roots from this and thousands of other herbaceous plants permeate the topsoil in lowland and streamside areas and prevent erosion.
There are four species in this genus in North America, but this is the only one known from Missouri. The other three occur mainly in the southeastern United States. Globally, some 15 to 30 species are known, mostly from tropical, subtropical, and warm-temperate regions.
If you're intrigued by this plant, note that two of the three North American Elephantopus species that are not known from Missouri do occur in nearby counties in northern Arkansas. There's a good chance those species might eventually be found in southernmost Missouri. Maybe you want to look for them. All share the unusual flowerhead structure, but both of these nearby Arkansas species have the leaves mostly basal at flowering time, with the stem leaves much smaller than the basal ones:
- Smooth elephant's foot, Elephantopus nudatus, has slightly smaller heads and achenes (seeds), and the pappus bristles (atop the achenes) are flattened and broadened to a triangular base (not broadening only gradually at the base).
- Hairy elephant's foot, Elephantopus tomentosus, has relatively large heads and achenes, and it has woolly pubescence (matted, intertangled hairs; not straight hairs) on the bracts subtending the flowerheads, sometimes also on the leaf undersurfaces.
Taxonomy: The sunflower/daisy/aster family (Asteraceae) is very large, with an estimated 23,000 species (or more) worldwide. Missouri has about 329 species in 104 genera. Botanists have divided the family into more manageable sections called tribes. Tribes are groups of closely related genera. Missouri's 104 genera fall into 11 of these tribes. Some tribes are rather intuitive, such as the sunflowers and their relatives, the thistles and their relatives, the thoroughworts and their relatives, and so on. Together, our one species of Elephantopus and our five species of ironweeds (Vernonia) are the only Missouri members of tribe Vernonieae, which we could call the "ironweed tribe."
