In Bloom: Painting a Pretty (Complex) Picture

Paintbrush is without doubt one of our most striking and beloved wildflowers. There are six species in our area, blooming from early spring to late summer, from the valley floor to the high alpine. Depending on the species, paintbrushes appear in various shades of red, yellow, orange, magenta, cream and pink. Sometimes they are more than one color; sometimes they are striped. This variation is likely the result of hybridization, which makes identification complicated.

And that’s just the beginning of the puzzling features this flower throws at us.

First, to call it a “flower” is almost a misnomer.

What we admire as the attractive Castilleja flowers are actually bracts, a type of modified leaf. The flower petals themselves are fused in a skinny, green tube that is distinctly un-flower-like (see Rosy paintbrush photo). The bracts do the job that flowers usually do: attract pollinators.

Which leads to another puzzling aspect of paintbrushes: most everything about them is NOT well designed to do this. Paintbrushes have almost no smell; they have poor landing platforms; they are often red, which most pollinators can’t see well; and their tubular flowers are difficult to access for most insects.

Enter hummingbirds: they have long bills and can hover. Their good fit with Castillejas suggests hummingbirds may have co-evolved with them.

This is critical since paintbrushes have no time to lose, pollination-wise. Castillejas are biennials, meaning they grow from seed one year, bloom the next, drop their seed for the next generation, then die. That’s a lot to do in two years.

Which brings in another fascinating, and complicating, aspect of their being.

Castillejas are hemiparasites, meaning that while they have green leaves and can photosynthesize, they also have the ability to steal nutrients from other plants. Paintbrush’s parasitic nature recently led botanists to move Castillejas out of its longtime family, the Figworts, into the Broomrape family, where other parasites and hemiparasites reside.

Apparently the Figwort family, which used to include Penstemons (now in the Plantain family) and Louseworts (joining Castilleja in the Broomrape) was a hodgepodge of misfits and has largely been disassembled.

But back to the Castillejas. Their specialized roots called haustoria penetrate the roots of other “host” plants, often sages or grasses, to find water and nutrients to pipe back to themselves, supplementing photosynthesis. Accessing the mature, deep roots of long-living, perennial plants assures Castilleja a ready source of nourishment and water, allowing them to grow vigorously during their short life.

It is that vigorous growth that fills our mountains with fields of paintbrush in a dazzling array of colors every summer. Look for them now below snow-loving passes like Buckskin in Aspen and Silver Creek in Marble.