I think it was two years ago now that I first noticed a compass plant or two or twenty in the Back Five. Their leaves are so distinctive that it's one of the few native perennials that's easy to identify, even without seeing it bloom.
About 18 months after we moved in, I attended a Lunchtime Lecture at Botanica where Brad Guhr of Dyck Arboretum was speaking. He had brought along several compass plant bloom spikes, with some open blooms, spent blooms and young seed on them. After the talk, he offered the bloom spikes to anyone who wanted them - I grabbed one? two? ten? (I can't remember now) and brought them home, scattering the seed in the Back Five. The young seed wasn't fully mature yet, so I wasn't sure if there was even a chance that any compass plants could establish.
But they have! The photo to the right is the first bloom spike for a compass plant that I have seen on our property! I took this shot on the 4th of July - a great American find on a great American holiday. I am 5'6" tall; this flower spike is my height or a little taller, just to give you a little sense of scale.
My seed-scattering history aside, I think this particular plant - and maybe one other one - may actually have predated my restoration efforts; these two plants are so large that they may be remnants from the original prairie here. On the other hand, most of the compass plants that I see now throughout my little acreage have two or three leaves this year and are far from blooming. Since compass plants are supposedly like trees, with a leaf for every year of life, at least when they are young, this plant would appear to be much older than our measly 5+ years of "occupation," while the littler ones would seem appropriate for seedlings from the seed Brad so generously shared.
The scientific name of compass plant is Silphium laciniatum, and this tallgrass prairie native is found throughout much of the middle of the country. Its common name is derived from its foliage: the large, thick, sandpaper-textured leaves with their deep lobes tend to align pointing north to south, minimizing the exposure of the leaves' sufaces to the hot, noonday sun, but capturing plenty of light throughout the mornings and afternoons. Pioneers apparently used this plant to help themselves navigate.
Although the basal leaves grow up to about 2' in width, the real size of the compass plant comes from its flower stalk, which can tower up to 12 feet above the prairie soil. The flowers look very similar to sunflowers, but if you look closely there is a major difference: unlike sunflowers, only the ray (or petal) flowers are fertile in these blossoms. Therefore seeds are only produced around the rim of the dried flower head.
Typical of a prairie native, the roots of compass plant grow very deep - up to 16' - helping it to survive dry times with panache. There would probably be more compass plants around except that cattle find it very tasty and will eat it to the ground so frequently that the plants soon lose all their energy stores and die. In the last few years, though, I've been seeing a fair number of compass plants along the roadsides in certain areas - on the turnpike south of Topeka, for example, and in Butler County along some of the country roads - where the main grazers are grasshoppers and bush hogs.
If you choose to plant compass plants in your garden, be careful about siting them correctly from the very beginning, as their deep tap roots make them hard to transplant once established. Know that they will grow quite tall and be sure to plan accordingly. For prairie gardens, they can be a particularly nice addition since their large leaves add a unique texture with a coarse feel, a rather unusual combination in the normally "medium" textured prairie palette.
Birds relish compass plant seeds and many use the dried stalks to perch on while they're overlooking the grasslands. There are even 2 species of insects, the silphium beetle and the prairie cicada, that are specialist feeders on compass plants and others in their genus. I have never seen either of these insect species, so I can't show you photos, but one of these days I hope to remedy that lack.
Compass plants flower from the top of the flower stalk down. Almost 3 weeks after I saw the original blooms, the flower spike looked like this on Monday. Busily munching away were these beasties....
...known as two-striped grasshoppers (Melanoplus bivittatus). Two-striped grasshoppers are common creatures of town and country. They can become quite destructive, eating a wide variety of plant material, including some crops such as alfalfa. Here they are performing their more classic function, acting as the primary herbivore (grazer) on the prairie - in this case, eating the flowers of the compass plants.
This morning I couldn't resist taking another photo of the compass plant. The drought and heat is even taking its toll on this stalwart prairie plant, but it's gamely continuing to bloom, even as some of its basal leaves turn brown and die. You can see that its bloom period is probably not quite half over, since the open bloom is about 1/3 of the way down the bloom stalk.
We have a 30% chance of rain tonight and tomorrow - the best chance we've had in weeks. We're all keeping our fingers crossed and doing literal and figurative rain dances. Wish us well!