If I could pick one genus of shade loving plants I would not want to live without, I would pick the foxgloves without a second thought. Thanks to Darrell Probst, Epimediums are far more numerous and variable (I'm tempted by these, I admit), Primula is fabulous, but most species of primrose need far too much irrigation to be practical for most people. Hellebores are terrific, but the flowers (except, of course, for H. niger) for all their improvement are still a trifle glum for my taste.
Ironically, the only foxglove commonly grown in "conventional" Denver gardens is D. purpurea, which is the least satisfactory in my opinion. It needs far more water than the other species to do well, and it is one of the few that is biennial. The one above came to me as Digitalis fontanesii, which has been lumped with D. grandiflora: the latter has a large range, and I suspect this is a regional variant--both are worth growing! [I stick to the old name because I see distinctions that evade the weary eyes of botanists poring over dried husks of plants]...
This is one of the many hybrids that have popped up over the years at our various gardens: this one at Plantasia at DBG: probably grandiflora crossed with ferruginea (see below), but I could be wrong. Alas, hybrids are almost always sterile!
My current favorite (probably because it is the one I have obtained most recently), Digitalis parviflora may have "parvi-" "floras", but they are bunched so charmingly, and the honey-amber-caramel coloration is irresistible. I believe I have seen this in quite a dark chocolate brown--a form I would love to grow as well.
Alas, my best pictures of this are still on transparencies: this has been ridiculously lumped with the common, tall Digitalis purpurea (supposedly as "var. purpurea") to which I say "pshaw!": this is utterly distinct from the giant biennial: it makes a much hairier, trim rosette, and produces distinctively shaped, wonderfully flared trumpets over a very long season--these can be deep, crushed raspberry red. It is a pretty long lived perennial (I have kept them five or six years), and loves dry shade. It superficially resembles the better known D. thapsi: I grow the two nearby one another and they are very different indeed.
This has been one of the highlights of this year: I finally have gotten Digitalis heywoodii ("D. purpurea var. heywoodii" according to the botanists.) Imagine a compact common foxglove, only with wonderfully gray foliage and crystalline white flowers....only it's perennial!
I finish with Digitalis ferruginea, another bronzy species that can tower to six or more feet tall. It thrives in a variety of sites and soils, and though the individual plants can be monocarpic, they invariably self sow and persist like sound perennials. The pale primrose color in the background is yet another foxglove, in this case Digitalis lutea, one of the smaller flowered sorts. But all indispensible...
And there are many more I have not discussed. All of these have settled down in my home garden to many niches. Did I mention that they make outstanding cut flowers? Easily grown from seed, and some can even be divided. They are tough and carefree and persist year in year out, blooming for months at a time, and looking clean and attractive even out of bloom. Each year my garden seems to have a few more patches of them.....but never quite enough!