Trollius laxus
American globeflower
Ranunculaceae (Buttercup family)
Blooming Trollius laxus, or American globeflower, is a sign of spring. Or, more accurately, spring-like conditions.
T. laxus pops up in the mountains, at the edge of the snowpack, just as it's starting to melt.
As streams swell with runoff, it mingles with Caltha leptosepala (marsh marigold) on the banks and even down into the water.
I took these pictures in early July. That's when the spring thaw comes to the Long Lake - Lake Isabelle area, just short of 11,000 feet in western Boulder County.
T. laxus is fairly easy to identify partly because of where it grows, and also because of its low, white or cream, "buttercup" flowers, its bunch of yellow stamens and its distinctively-lobed leaves.
Inflorescence
The flowers are pretty big -- between 2.5 and 5 cm. across. The showy "petals" aren't actually petals. They're overgrown sepals. Or, as a botanist would put it, "petaloid sepals".
The number of petaloid sepals on a T. laxus flower varies. There can be as few as 5 and up to 9. The sepals are ovate (egg-shaped). They first bloom white, then turn creamy and even greenish as the plant matures.
The sepals are what you notice, but T. laxus does have petals -- quite a few of them. They're just not as conspicuous. They're yellow, which camouflages them behind the tangle of yellow stamens.
The stamens are about twice as long as the petals and about half the length of the white sepals.
Leaves
The flowers are at the top erect stems that can be anywhere from a few centimeters to a meter tall. All the ones I've seen have been short.
T. laxus has both basal and cauline leaves. The basal ones are 4 - 8 cm wide and on petioles that can be from 5 - 30 cm long.
Farther up the stem there are usually 1 - 3 and rarely up to 5 palmate, deeply-lobed and toothed cauline leaves. The cauline leaves are sessile and kind of clasp the stem.
The full name of the plant is:
Trollius laxus Salisb. ssp. albiflorus (A. Gray) Á. Löve & D. Löve & Kapoor.
It's a mouthful, but to refer to the version of this plant in Colorado (and the Rocky Mountain west) you have to use at least through ssp. albiflorus. It has an estranged subspecies, T. laxus ssp. laxus, which is isolated in a few mid-Atlantic states.