Organic Pest Control, the Mad Botany Way

So, there was an outbreak of fruit flies in the kitchen last week. The place looked like an introductory genetics lab in May, when the students start to get lazy about disposing of their old Drosophila cultures. After more prosaic control options--such as cleaning out the compost bucket--were exhausted, I starting thinking about the possibilities for mopping up the abundant fruit fly stragglers. If only I had something sticky like flypaper, with a sweet smell to draw the insect pests to their doom...


Then I remembered that I have access to Drosphyllum lusitanicum, the Portuguese Sundew or Dewy Pine, a large carnivorous plant from the western Mediterranean with leaves that drip with mucilaginous goo and smell strongly of honey.


Drosophyllum turns out to be brutally efficient at offing Drosophila. The first flies were caught before I even set the plant down by the sink, and within an hour it looked like the majority of the infestation was glued to the leaves and in the process of being digested. I brought the Drosophyllum back to its greenhouse lair after a couple of days: it's not the sort of plant that would survive in typical kitchen conditions for long. Besides, there wasn't anything left for it to eat.

For those tempted to try growing their own Drosophyllum, there are cultural notes at the ICPS website.

Hail to the King, Baby

Drosera regia in cultivation in Connecticut, June 2009. Leaves about 40 cm (16 inches) long.

Drosera regia, the King Sundew, is one of the giants among carnivorous plants, apparently growing close to a meter tall in some situations. Its natural range is a small patch of mountainous terrain north of Cape Town, South Africa, and it occupies an evolutionarily isolated branch of the sundew family tree, being the only surviving representative of a very early-diverging lineage. King Sundews are uncommon in cultivation, having a reputation for being slow-growing and temperamental. These plants at the University of Connecticut were started from seed collected in Bainskloof, South Africa, and are flowering for the first time at age 4.

Drosera regia flower.

I had several individual King Sundews flowering at the same time, so I cross-pollinated them. Six weeks later, the first seed capsules have started to ripen, and it looks like pollination was successful. Even seeds are big in D. regia: about the size of poppyseed, which is gigantic by Drosera standards.

Drosera regia, ripe capsule and seeds (pencil tip for scale).

Jerry Barad's 53rd Open House

Jerry Barad discusses salvaging plantlets from a favorite variegated Agave potatorum, which was in the process of dying after it flowered.

For more than half a century, Jerry and Bea Barad have been hosting an annual open house at their spectacular private collection of cacti and succulents in New Jersey. This year, the Massachusetts and Connecticut cactus clubs decided to work together to charter a bus down to Jerry's place for the big event.

Dr. Barad made a living as a gynecologist before his retirement, but in his free time he is also a serious student of succulent plants who has traveled extensively in the Americas, Africa, the Middle East and the Canary Islands, and published his findings in national and international journals. His area of specialization is stapeliads (succulents in the Apocynaceae, or milkweed family), but he grows pretty much everything. Outside of stapeliads, his collections of Haworthia and Echeveria are especially impressive.

Stapeliad festival.

Stapelia vetula, which has dropped some of its milkweed-like seeds to the left of the flower.

Jerry has two greenhouses. The smaller one is devoted mainly to the Crassulaceae: Echeveria, Crassula, and other members of the stonecrop family. The larger, older greenhouse is divided into halves, with a warm section given over to stapeliads, pachypodiums and other more tropical plants, and a cooler section with cacti, Haworthia, mesembs and more.

Variegated Haworthia truncata. Nothing that a little 2, 4-D wouldn't clear up. I'm not a fan of variegates, but actually, that is impressive.

Outside of the greenhouse, the grounds are like a miniature botanical garden/zoo, with hardy cactus and succulent rockeries, koi pond, bamboo grove, orchards, sheep pasture, a giant vegetable garden and carefully tended borders with annuals and dozens of large Brugmansia (Angel's Trumpet) plants that are planted out every spring, then dug out and stored in a cool garage all winter. It must be an enormous job to take care of it all, but Jerry does have hired help.

The view from the house. The greenhouses are behind the clump of bamboo (Phyllostachys aureosulcata?) at left.

The trip went smoothly, and I think everyone had a great day photographing plants, meeting fellow enthusiasts from all over the region, and just lounging by the pool. I'll be looking forward to visiting the Barads again some time!

Connecticut visitors Martha B., Bill B. and Ken M. between the koi pond and the swimming pool.

Echeveria and other Mexican Crassulaceae in the smaller greenhouse.

Impatiens mirabilis, a semi-succulent lithophyte (plant that grows on rocks) from tropical Southeast Asia.

Euphorbia piscidermis, a remarkable example of evolutionary convergence with the unrelated cactus genus Pelecyphora.

Me next to a giant Adenia (A. fruticosa?), which apparently grew from a piece of stem that Jerry left by the post many decades ago.

Carnivorous Plants at Tolland Marsh Pond

Tolland Marsh Pond, May 31, 2009. Sarracenia flower at lower center.

Tolland Marsh Pond is a rather large (half a mile north to south) wetland, located in my neighborhood in the northeastern corner of Connecticut. The waters of the pond itself are acidic and dark, and ringed with a wide swampy margin of sedges, sphagnum moss, and thickets of blueberry and buttonbush. This is the kind of place where carnivorous plants grow, and in a recent trip to the pond I managed to find several different species of insect-eating greenery.

Sarracenia purpurea ssp. purpurea. Note mosquitoes in lower left pitcher; these may be Wyeomia smithii, a pitcher plant commensal.

The most impressive carnivorous plant native to New England is the Purple Pitcher Plant, Sarracenia purpurea. The pitcher plants were in full bloom when I checked them in late May. The dark maroon flowers attract pollinating bees, and are held well above the modified, water-filled leaves.

Sarracenia purpurea flower, about 2 inches across.

The leaves are the business end of the plant; the part that actually traps and kills insects, then breaks them down in order to obtain nitrogen and other nutrients that are in short supply in bogs. Unlike some carnivorous plants, Sarracenia purpurea does not move. Prey is attracted by the coloration of the leaf and nectar that it secretes. Unlucky critters slide into the pool of liquid inside, drown and are digested by bacterial action.

Pitcher plants and cranberries. The fruit must have come through the winter, but it was still edible, if a bit mushy.

At Tolland Marsh Pond, pitcher plants are present in a few open, boggy areas, but don’t seem to be tremendously abundant. I’ve seen a few dozen plants, but there are large areas of potential habitat that I haven’t checked.

Drosera rotundifolia. A few plants of this species are visible in the cranberry photo above, too.

Drosera intermedia favors wetter, muckier parts of the bog.

The pond is also home to both of the species of sundew that occur in inland Connecticut, Drosera rotundifolia and D. intermedia. Sundews have glandular tentacles on their leaves that secrete sticky mucilage, and trap small insects. The tentacles and leaves slowly fold around and digest their prey. Drosera rotundifolia grows all around the pond in sphagnum moss, or on half submerged waterlogged wood. Drosera intermedia isn’t as widespread, and I saw just a few patches of it in mucky peat in open areas on floating mats of moss and vegetation.

Tolland Marsh Pond: edge of the marshy parts of the area viewed through laurel thicket, White Oak and Red Maple. There is a pond out there, but you can't see it from here.

Tolland Marsh Pond isn’t easily accessible, which does have the beneficial effect of limiting the number of visitors to a fairly fragile habitat. There are a few informal trails around the pond, but my botanizing has involved a good deal of bushwhacking through laurel thicket (Mountain Laurel is pretty, but it is a slow and scratchy process to cross a dense stand of it). The marshes where the carnivorous plants occur are treacherous as well, with floating hummocks and sphagnum mats providing doubtful footing over sunless water and peat slurry of indeterminate depth. Tolland Marsh Pond also has Poison Sumac (Toxicodendron vernix), which is a bit like Poison Ivy, but twice as toxic and as tall as a lilac. Nasty, nasty stuff, which normal people will fortunately never run into, since it is almost entirely confined to bogs.

Tolland Marsh Pond, January 2009.

Sarracenia purpurea is evergreen, and although the leaves are low to the ground and can be hidden by even a little snow, the old seed heads are distinctive and fairly tall. So, winter is a good time to explore bogs for Purple Pitcher Plant populations. Places that are inaccessible in summer--too solid to be navigable by boat, but too unstable to negotiate safely on foot--can be reached by an easy walk after a long cold spell has frozen the landscape solid. And, there are no leaves on the Poison Sumac to worry about brushing up against.

Two Sarracenia purpurea flower stalks sticking above the snow (lower left and center).

I first found pitcher plants at Tolland Marsh Pond by taking advantage of good conditions for frozen bog walks this past winter. It would have been easier to find the plants if there hadn't been so much snow, but the old seed heads are fairly easy to spot, and seem to persist well into the cold season. There were even seeds still present in the capsules in January.

A little digging reveals the rest of the plant. Sarracenia purpurea leaves tend to turn solid red in winter, possibly to protect against light damage while the plants are dormant. The pitcher plants that I've seen in winter at Tolland Marsh Pond were close to open water in the center of the wetland, while the ones that I've been able to check on in summer were near solid land around the edge. In between, there is a stretch of possible habitat where I haven't looked. Time to think about another expedition!

Aloe dichotoma: the Quiver Tree

An Aloe dichotoma forest east of Ratelpoort, Northern Cape, South Africa (August, 2004).

In Namaqualand, in the arid northwestern corner of South Africa, about the closest thing to a forest that a traveler in search of shade will find are groves of Quiver Trees—Aloe dichotoma, or Kokerboom in Afrikaans—growing on rocky slopes. At about 10 to 20 feet high, Quiver Trees are giants of the succulent plant world, if on the small side by ordinary tree standards.

The forest of Aloe dichotoma in the photo is located near Ratelpoort in central Namaqualand, where some of the finest stands of this species that I have seen occur. Quiver Trees are widespread in the arid parts of southern Africa, growing naturally throughout much of the Northern Cape Province in the RSA, and north well into Namibia. There is quite a bit of variation in the form of the plants, and a short, highly branched form found in the northern part of the species’ range is sometimes recognized as a separate entity, Aloe ramosissima.

The common names Quiver Tree and Kokerboom both refer to the former usage of hollowed-out A. dichotoma stems as containers for arrows, by Khoisan people. Aloe dichotoma has been put to other ethnobotanical uses, as well. In the not too distant past in the hinterlands of South Africa, farmers without electricity would fashion A. dichotoma wood into boxes that served as crude refrigerators. The wood is very light and porous, and if kept wet by a drip of water a Kokerboom container apparently stays quite cool from evaporation. I actually saw a Kokerboom refrigerator outside of a farmhouse in Bushmanland, years ago, though the device had been idle for some time.

Aloe dichotoma seedling, about a foot high at four years of age.

The homeland of the Quiver Tree receives its rain in winter, for the most part, but cultivated A. dichotoma plants pretty much seem to grow whenever water is available. Ordinary cactus and succulent soil mixes and watering regimes seem to work well with the Kokerboom, though it is not nearly as tolerant of poor light as its houseplant cousin, Aloe vera. Seed is usually available from Silverhill Seeds, and can quickly yield nice little plants, especially if the seedlings are given plenty of root run. I started my seedlings in the autumn, though I wouldn’t be overly surprised if it was possible to germinate seed in other seasons.

Aloe dichotoma with Connecticut Yankee for scale. The landscape, with domes of red gneiss/granite, is typical of Namaqualand. This is the farm Namaras, southeast of Springbok (July, 2004).