Penstemons

What’s blooming in the area: Dr. Huey and hybrid tea roses, trumpet creeper, Japanese honeysuckle, silver lace vine, red yucca, daylily, Russian sage, hollyhock, datura, sweet pea, larkspur, squash, alfalfa, brome grass; fresh peas for sale.

Beyond the walls and fences: Tamarix, Apache plume, cholla cactus, Virginia creeper, showy milkweed, fernleaf and leatherleaf globemallows, cheese mallow, scarlet bee blossom, white evening primrose, velvetweed, bindweed, stickleaf, purple mat flower, goat’s head, white sweet clover, buffalo gourd, silver leaf nightshade, western goat’s beard, Hopi tea, golden hairy and strap-leaf spine asters, native dandelions; buds on prickly pear.

In my yard, looking east: Persian yellow rose, winecup mallow, sidalcea, coral bells, baby’s breath, snow-in-summer, sea pink fading, Jupiter’s Beard, Maltese cross peaked, bouncing Bess, pink evening primrose, pink salvia, Saint John’s wort.

Looking south: Floribunda and rugosa roses, oxalis, tomatilla; begin to see color on raspberries.

Looking west: Lilies, Husker Red and Rocky mountain beardtongues, blue flax, catmints, flowering spurge, sea lavender; buds on white mullein and ladybells.

Looking north: Catalpa fragrant in evening, golden spur columbine, coral beardtongue, Hartweig evening primrose, butterfly weed, Mexican hat, Moonshine and Parker’s Gold yarrows, chocolate flower fragrant in morning, coreopsis, blanket flower, anthemis, black-eyed Susan; buds on chrysanthemum.

Bedding plants: Sweet alyssum, pansy, snapdragon, moss rose, impatiens, nicotiana.

Inside: Zonal geranium, aptenia, asparagus fern.

Animal sightings: Hummingbird, house finch in four-winged saltbush, other small birds, bumble bee, smaller bees on columbine and catmint, hornet, cabbage butterfly, small flying insects, small black ants on Virginia creeper flowers, harvester ants, uncover earthworm; hear crickets.

Weather: Hot afternoons fed the Pacheco fire which could be seen from my back porch; although most of the smoke blew in other directions, some particles still filtered my way; last rain 5/19/11; 15:57 hours of daylight today.

Weekly update: God the great clockmaker has been transformed into an ergonomic engineer.

Botanists agree on the general characteristics of the Penstemon product line. They have funnel shaped flowers arranged in spikes. A pair of stamens lie under each of the two upper petals. A sterile stamen sits above the middle of the three lower lobes. The pollen bearing anther pads tend to be at the front. The luring nectar source lies at the back behind a pinched waist.

When scientists look at individual species they see design changes made to accommodate the differences in pollinators. Color, shape and nectar are the elements they use to define niche markets.

The bright coral-red Penstemon barbatus coming into bloom on the north side of the house has been adjusted for humming birds. Its long, narrow corolla tube is pointed down, its lower lobes pulled back. The stamens have no hairs to obstruct movement to the nectary filled with diluted sucrose. The birds, which feed in flight, incidentally bump the anthers and fertilize the stigmas.

The other common beards tongues are for bees. The foxglove penstemon blooming on the north side of Santa Fe, where it apparently was introduced by someone from the humid southern plains, has a much larger tube to accommodate bumble bees. The five lobes flare back, the anthers are white, but the staminode is a large, humped golden brush that forces the bee to move above it and collide with overhanging stamens.

The exterior color of the local Penstemon cobaea is pale pink, but the interior of the upper petals is purple. Darker purple stripes mark the center veins on the lower lobes. Like the coral beardtongue, the plants have tall stems and most plants growing along side the road have only one or two. They tend to be about 2' apart.

The purple colored Rocky Mountain beardtongue blooming on the west side of the house is fertilized by a variety of bees. The upper lobes are pulled back, but the lower ones, with lighter colored lines, protrude to form a landing platform. The tube itself is shorter, the nectar scarcer and more concentrated than barbatus.

Penstemon strictus anthers are dark, but covered with white hairs. The sterile stamen is white with white hairs. The shorter stems grow above clumps of green foliage that make it easier for the bees to go from stalk to stalk, spreading pollen from one flower to another.

Engineers rarely work in isolation. One of their special challenges is to alter an existing object to make it appealing to some new market. Penstemons emerged in the Rockies, and spread from there south and east.

Coral beardtongues grow in the mountains of Colorado and Utah, Arizona, New Mexico and Texas. Rocky Mountain penstemons have a slightly larger appeal, reaching a bit farther north into Wyoming. The foxglove species lives on limestone soils between the Mississippi and the mountains.

When it reached the Mississippi, the genus faced new challenges that required more tinkering. The Penstemon digitalis cultivar going out of bloom by the garage has twelve sets of four chromosomes, instead of the usual two. Although it seems to prefer glacial soils around the Great Lakes, it has spread to most parts of the eastern United States and Canada.

The latest master mechanic has been Dale Lindgren, recently retired from the University of Nebraska, where he experimented with the smooth penstemon to develop Husker Red with its maroon colored leaves. He later crossed it with Prairie Splendor, itself a cross of cobaea and triflorus, and patented the result as Dark Towers for the university.

My Husker Red has relatively small, white flowers tinged by purple hairs on the outside, near the bulbous base which contains mainly sucrose. The lower petals extend farther than the recurved upper ones, the anthers are dark, and the staminode white and hairy. In 15 years, it has expanded into a clump that produced 18 short stalks this summer.

Engineers like to reduce complexity to simple rules. Despite the number of variables they’ve used to attract consumers, they’ve learned color is the only trait they notice. Hummingbirds see more red, bees more ultraviolet. Although digitalis flowers are white, Gregg Dieringer and Leticia Cabrera found that all parts reflect UV light except the purple lines in the center of the petals.

In Missouri the species is pollinated by bumble bees, while smaller halictid bees are common visitors in Ohio. In Illinois, Gregg Dieringer and Leticia Cabrera observed mainly small and medium bees. When no bee succeeds, the flowers in Missouri are capable of fertilizing themselves.

Once a product succeeds, engineers are often tasked by their employers with reverse engineering the work of their competitors to determine how they work and how they’re made. A team led by Maria Clara Castellanos altered strictus flowers one trait at a time, until they resembled those of barbatus to see which, in fact, were important to hummingbirds and which to bees. Dieringer and Cabrera removed the fifth stamens of digitalis to see what affect they had on bees.

Both groups found evidence that supported their theories. They also found the engineering was more complex than they expected, and the customer-product relationship more malleable to changing circumstances.

Notes:
Castellanos, Maria Clara, Paul Wilson and James D. Thomson. “‘Anti-Bee’ and ‘Pro-Bee’ Changes during the Evolution of Hummingbird Pollination in Penstemon Flowers,” Journal of Evolutionary Biology 17:876-885:2004.

Dieringer, Gregg and Leticia Cabrera R. “The Interaction Between Pollinator Size and the Bristle Staminode of Penstemon digitalis (Scrophulariaceae),” American Journal of Botany 89:991-997:2002.

Hubbard, John P. “Penstemon spinulosus Wooten and Standley: New Mexico Endemic, Error or Introduction?,” The New Mexico Botanist, 6 July 1999; on Penstemon cobaea around Santa Fe.

Wolfe, Andrea D., Christopher P. Randle, Shannon L. Datwyler, Jeffery J. Morawetz, Nidia Arguedas and Jose Diaz. “Phylogeny, Taxonomic Affinities, and Biogeography of Penstemon (Plantaginaceae) Based on ITS and cpDNA Sequence Data,” American Journal of Botany 93:1699-1713:2006.

Photograph: Two Rocky Mountain beardtongue flowers, one open, one spent; 25 June 2011.

Coral Beardtongue

What’s blooming in the area: Tea and miniature roses, Apache plume, rose of Sharon, hedgehog cactus, yucca, buddleia, Russian sage, trumpet creeper, honeysuckle, silver lace vine, purple phlox, bigleaf globemallow, white sweet clover, alfalfa, oxalis, milkwort, velvetweed, white and yellow evening primroses, scarlet beeblossom, stickleaf, goat head, silver-leaf nightshade, bindweed, buffalo gourd, zinnia, cosmos, purple coneflower, wild lettuce, horseweed, local dandelion, Hopi tea, hairy golden aster, plains paper flower; farmers, garden, and plains sunflowers; catalpa pods lengthening; corn beginning to form.

What’s blooming in my garden, looking north: Golden spur columbine, coral beardtongue, hartweig, butterfly weed, yellow flax, chocolate flower, fern-leaf yarrow, blanket flower, coreopsis, anthemis, black-eyed Susan, Mexican hat; buds on perky Sue.

Looking east: Large-leaf soapwort, bouncing Bess, snow-in-summer, coral bells, ipomopsis, tomatillo, California poppy, hollyhock, winecup, sidalcea, pink savlia, pink speedwell, rock rose, pink evening primrose, Jupiter’s beard; buds on cutleaf coneflower, sedum, and garlic chives.

Looking south: Blaze, tamarix, Illinois bundle flower, sweet pea, daylily; rugosa rose hips forming.

Looking west: Catmint, ladybells, perennial four o’clock, flax, speedwell, purple ice plant, white spurge, sea lavender, Shasta daisy; buds on caryopteris and Monch aster.

Bedding plants: Snapdragon, sweet alyssum, petunia, moss rose, Dahlberg daisy, French marigold, gazania.

Inside: Aptenia, bougainvillea, zonal geranium.

Animal sightings: Hummingbirds, swallowtail butterfly, dragonfly, squash bug, grasshoppers, ants, bees.

Weather: Afternoon clouds, with their high winds, actually dumped rain several nights; morning temperatures still fell to 60; 15:30 hours of daylight today.

Weekly update: Hummingbirds are a bit like cats. They seem to know the people who don’t want them and elect to torment them.

This past weekend, their number increased dramatically around the house, perhaps because the young were beginning to feed. Usually five weeks pass after a mother lays two eggs before the fledglings begin foraging. I first saw a pair of small birds about six weeks earlier on May 20th.

Once the young can fend for themselves, the females may mate again. In the past week at least one pair has been darting about, often diving within a few feet of where I’m standing, unseen but sensed by their sound and changing air currents.

Many of my neighbors keep red plastic feeders. When they ask me if I feed the birds I say no, but with my fingers crossed behind my back. The birds have sown their own food and, because coral beardtongues are attractive, I let them be.

I first planted Penstemon barbatus in 1995 with no luck. I tried them again in 1996 in a different location where they held on, but didn’t increase. I added more the next two years, but didn’t see any evidence they had settled until 1999. Around 2002 they appeared on the north side of the house among the tiles and since have colonized that scree environment.

Andrea Wolfe and her confreres used DNA to confirm Penstemons evolved in the Rocky Mountains, and spread from there to the southwest, probably adapting to conditions created when the glaciers retreated in the Pleistocene. Scarlet Bugler grows west of the New Mexico continental divide, and along the Rio Grand north from Albuquerque and to the northeast. The 6000' Española valley is at the low end of its preferred range between 6000 and 9600 feet.

Despite their origin in commercial production, my plants have maintained their alpine habits. Not only can the grayish stalks withstand severe winds without bending or breaking, without becoming stunted or dessicated, the perennials retain their leaves in winter. The basal rosettes turn purplish-red when photosynthesis slows and the bluish-green fades.

Penstemons, as a group within the snapdragon family, have been particularly sensitive to the needs of their pollinators, converting from bees to hummingbirds at least ten times. Coral beardtongues have lengthened and narrowed their flower funnels, and reconfigured their lower lips so they don’t provide landing platforms for insects.

The flowers stay in bloom for months, even if the color fades a little: last year they persisted until mid-September, the year before the end of August. Unlike many flowers which immediately convert to seed production, these refill their nectaries and replenish the pollen so hummingbirds can continue feeding and pollinating. However, they keep the food levels low so the animals must dart from stalk to stalk.

I assume this is less a sensitivity to the needs of birds than a reproductive strategy by a plant that can’t fertilize itself. What seed it produces in its hard, sharp cases can be erratic: it not only needs cold winters, but Scott Abella found exposure to ponderosa smoke helps. Before my plants naturalized there was the Cerro Grande fire of 2000 followed by a snowy winter and forest fires in Arizona the following summer which I could smell for a week.

Coral beardtongues are native plants that can grow in gardens in many parts of the country, but there they are maintained by cuttings. It was only when nature, abetted by the birds and man-made fires, could reproduce ancestral conditions that my plants went from choice specimens to genuine wildflowers that could sustain themselves and hummingbirds unaided.

Notes: I suspect the birds are black-chinned hummingbirds. However, the ones I see have the limited coloring of females and juveniles that make it difficult to be sure of species.

Abella Scott R. “Effects of Smoke and Fire-related Cues on Penstemon barbatus Seeds," The American Midland Naturalist 155:404-410:2006.

Lange, Ronald S., Summer A. Scobell, and Peter E. Scott. “Hummingbird-Syndrome Traits, Breeding System, and Pollinator Effectiveness in Two Syntopic Penstemon Species,” International Journal of Plant Sciences 161:253-263:2000.

Newfield, Nancy L. and Barbara Nielsen. “Black-Chinned Hummingbird” in Hummingbird Gardens: Attracting Nature's Jewels, 1996.

Wolfe, Andrea D., Christopher P. Randle, Shannon L. Datwyler, Jeffery J. Morawetz, Nidia Arguedas, and Jose Diaz. “Phylogeny, Taxonomic Affinities, and Biogeography of Penstemon (Plantaginaceae) Based on ITS and cpDNA Sequence Data,” American Journal of Botany 2006;93:1699-1713.

Photograph: If anyone ever doubted nature’s perverse joy in refusing to replicate scientific findings, yesterday a swallowtail was feeding on my coral beardtongues while the hummingbirds swooned through.