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Scutellaria — skullcap

The genus

Scutellaria is a genus of about three hundred species, including mostly annuals and herbaceous perennials, and a few subshrubs. They are distributed widely across the temperate regions of the planet, and also occur in tropical regions at high altitude. They are classified in the huge mint family (lamiaceae), but unlike many of their cousins, they're not known for their fragrance.

The genus name derives from the Latin word scutella, which means a little shield, dish or saucer - describing the little dish-like fruiting bodies left behind when the flowers fade. The common name refers to the flower itself, whose bottom calyx resembles a tiny medieval helmet.

the little dishes

I doubt scutellaria will ever be the object of massive gardening passion, like roses, hostas, daylilies, or even cranesbills. But I've developed a low-level collecting habit towards the genus - I'm intrigued enough to attempt any new variety that comes my way through seed exchanges. Through the years, I've tried my hand at many - not all successfully, mind you. Expect to see updates to this page as new ones enter our garden and strut their stuff!

I'll be describing the skullcaps growing in our garden in the rest of this page. Nearly all of them came from seed that I received in trades and exchanges; it is quite possible that my identification is off for a few species. If you see any evidence of mis-identification, please let me know using the email link at the bottom of the page!

Habit and cultivation

The statures of scutellarias growing in our garden range from little ground-hugging things to medium-height upright plants - none much taller than about two feet. Some of them have been downright easy to keep alive and happy, while others seem to fade quickly. I've not yet figured out if that's because of natural differences in life span, or because I failed to provide the proper conditions for the species in the latter group to thrive.

The skullcap that's graced our garden longest is S. incana, which we picked up a the Bowman's Hill wildflower sale many years ago. It still happily occupies the same space in our garden; every year I'm afraid it finally gave up (it's late to return in spring), but so far so good. Another one with staying power is S. altissima - although I'm not sure if it's the original plants that keep returning, or whether their place is taken by their generous offspring. In any case, our patch remains strong year after year.

The smaller varieties have been shorter-lived, in my experience. S. baicalensis was among the first we tried. It's gorgeous, but only lasted two or three years. Several attempts to re-establish it were unsuccessful (I think it insists on good drainage, which I cannot always provide), but finally this year we have flowering plants again. Even smaller is S. pontica, which defied its billing as a perennial, behaving instead as a biennial for us.

So I'll be experimenting with placement in years to come. One skullcap, the little woody-stemmed S. alpina, has already made its way into our rock garden, which provides the best-drained conditions our garden can offer. This may also be the best location for S. baicalensis, S. orientalis, and S. scoridifolia.

On the other hand, some like it wet - most notably, S. galericulata (marsh skullcap) grows along the waterside; we have ours planted in a pot set right in our big pond's filtration bog, where its soil is consistently wet. It seems quite happy there.

Propagation

All of my skullcap multiplication efforts proceed via seed. I wish I could give you a single method for germinating scutellarias, but it's not that simple. Some species germinate easily and in great numbers; others only grudgingly yield a seedling or two from multiple attempts, even after lengthy cold treatments.

I've had reasonable success germinating S. altissima and S. pontica without any cold treatment. S. baicalensis I've given about two weeks cold before germinating at room temperature. All others have been more recalcitrant; I have come to accept that S. incana needs about three months cold - given that treatment, it germinates nicely when returned to room temperature. The same probably holds for several other species that have been reluctant to sprout for me.

I share all of the detailed information on my germination attempts on the portrait pages for the individual species (linked in the captions of the tables below). Eventually, I hope I'll be able to provide good directions for a larger number of species.

Oh, the seeds themselves? Little dark balls. The fall out of their scutellas easily, so be sure to harvest them not too long after they ripen - which is when the dishlets turn crispy - tan or brown. I don't have enough of an experience base to know how long the seeds remain viable - but in at least one case (for S. baicalensis), year-old seed germinated fine, while the same lot a year later failed to germinate at all. Fresher is almost certainly better.

The leaves

Skullcaps are not known for their brilliant foliage. But even though they are mostly grown for their blooms, there's enough variety in leaf appearance to take a closer look. On all members of the genus, leaves are arranged oppositely (in pairs along the stems). All the ones we grow are leafless in winter. The photos below illustrate some of the variety:
Downy skullcap (S. incana) has crinkly, elongated, gently serrated leaves in a muted shade of dark green. Attractive without drawing attention to itself. Tall skullcap (S. altissima) is apple-green, with slightly sharper serrations on triangular to ovate leaves. A stand of these creates a bright green swarm in the garden, looking good even when not in bloom. Chinese skullcap (S. baicalensis) features smooth, entire-margined, mid-green leaves. Some of our plants (particularly youngsters) have narrower leaves than shown here.
S. orientalis makes a marvellous mat of small glossy leaves, attractively serrated. Alpine skullcap (S. alpina)'s woody stems sprout small gray-green leaves - similar in shape but not size to those of S. altissima. S. pontica, another low-growing type, has small leaves with more gently scalloped margins.
Marsh skullcap (S. galericulata)'s leaves are triangular and just a bit smaller than those of S. altissima - but slightly pointier. Prairie skullcap (S. resinosa) has small, slightly felted, smooth-margined gray-green leaves.

Flowers

Even though most of the diversity in appearance derives from the plants' habits and foliage, the flowers are the primary reason most of us grow scutellarias. Many of them, viewed up close, have a bit of a funny-face look to them. It's the muppet show! The mini-gallery below shows some of the blooms:
S. incana sports bicolor flowers with a nice contrast between clear blue and crisp white. Another bicolor, S. alpina is quite a bit different - not only in the rose color, but also the pattern and the way the flowers are clustered at the stem tips. S. baicalensis takes the bicolor thing to a much subtler level - from a distance, they just look like a royal blue. S. altissima continues the blue theme in a slightly more muted tone, with flowers that are conspicuously arranged in pairs along one side of the flowering stem.
Temporarily breaking up the blues, here's S. orientalis with its soft-yellow flowers held just barely above the leafy mat. Returning to icy blue, S. galericulata also sports the one-sided pairs look. The magenta flowers of S. pontica are held along one side of the stem, and show just a touch of white on their lower lips and along their tubes. S. resinosa's flowers are pretty close to a clear true blue, with subtle white highlights.

Other species

Roughly divided into two categories: those that I've tried to grow (but failed), and those I've yet to try. In the first category we have S. diffusa, a lavender-flowered annual, S. lateriflora (which has thwarted many of my seed attempts), and S. ovata. I thought I had S. wononowii, but it turned out to be S. altissima (or so I believe).

In the not-tried category, S. suffrutescens carries marvellous magenta flowers over a small-leaved low-growing mound - but it is hardy only to zone 7. 'Violet Cloud' is one of the few hybrid skullcaps I know of, with deep-violet flowers. It should be hardy to zone 6 at least. S. integrifolia is a US wildflower with narrow leaves and blue blooms.

There are many more - these are just some of the more garden-worthy species I'm aware of. If you have others to recommend, please use the comment form below.

Further reading

Wikipedia entry with some basic information about the genus.
The Open Directory Project's collection of links features mostly references to photographs of various species.
A paper describing possible medicinal uses, also including general, cultivation, and propagation information.
Alpicola: A Japanese page showing photographs of two dozen species.


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Last modified: June 09, 2012
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