Viscum minimum: a Dwarf African Mistletoe

Viscum minimum fruit emerging from its host.

Parasitic plants, which obtain some or all of their water and nutrients by attaching to a free-living host plant, seem to be unusually well represented in the floras of desert regions. Mistletoes (genus Viscum), probably the most familiar of vegetable parasites, may be encountered in arid places (and elsewhere) in the old and new worlds. Mistletoes are usually hemiparasitic, meaning that they extract water and minerals from their host, but are green and can manufacture some of their own nutritional needs via photosynthesis, like ordinary plants.

Viscum minimum is a minuscule mistletoe endemic to South Africa, where it grows inside of the succulent stems of euphorbias. Most of the time, V. minimum grows internally, with no indication of its presence on the exterior of the host plant. However, when it reproduces, the mistletoe’s greenish flowers and showy orange-red berries break through the euphorbia’s skin, in order for pollination and seed dispersal to take place.

Old plant of Euphorbia polygona ‘Snowflake.’

Viscum minimum is one of the few types of mistletoe that is ever cultivated outside of its native land. The host plant, usually Euphorbia polygona, is an easy to grow and attractive addition to a greenhouse or windowsill succulent collection. The mistletoe, which can be acquired either in the form of an infected euphorbia cutting or by smearing fresh, sticky seeds onto the surface of a suitable host, doesn’t cause significant harm to its host plant, and will produce crops of colorful fruit in time for the holidays year after year.

Frozen Flytraps

Connecticut got its first slushy snowfall of the season yesterday, and I took this photo of the Venus' Flytraps (Dionaea muscipula) in pots outside of the UConn biology greenhouses. They'll be fine, and can in fact take quite a bit more cold than this. Flytraps aren't tropical plants at all, and in their native land (the coastal Carolinas), they are dormant in winter and receive a fair amount of frost, and the occasional snow. New England winters might be too much for them, though, especially fully exposed to the elements in pots out of the ground, so I'll soon move them to a refrigerated room (temps just above freezing) for a couple more months of cold dormancy.

Planted in the ground, Dionaea can sometimes survive winters in southern New England, even without mulch or other extra protection. I've seen plants make it through several years in local bog gardens, though they seem to suffer a bit in colder than average years, and don't come back in spring 100% of the time. With a mulch of pine needles, they seem to be pretty reliable.

Eriospermum paradoxum

Cool nights and shorter days mean that winter-growing succulent plants are becoming active. Here is a pot of Eriospermum paradoxum, a tuberous plant from South Africa, blooming in cultivation in Connecticut. The flowers have a very strong fragrance, reminiscent of narcissus. After the flowers are finished, the tubers produce small leaves with a branched outgrowth that resembles a miniature Christmas tree. The leaves last until April or so, gathering weak winter sun to fuel the growth of the subterranean tubers, which will survive the summer heat in a dormant state before flowering again next autumn.

Fungus Among Us

Calostoma cinnabarina

I think that the rain last week has been encouraging our mycelial forest friends, and over the weekend I found a bunch of these strange objects growing in the woods along the Fenton River in Mansfield Center. After a bit of poking around in mushroom books, I'm fairly confident that they are Calostoma cinnabarina, or Pretty Lips, a fungus with some similarities to puffballs, though apparently the two are not related. A gelatinous protective layer and inner membrane peel away from the puffball part when the spores ripen, creating a little pile of tapioca-looking jelly with curled up bits of membrane in it.

Sunflowers

Helianthus annuus 'Mammoth Russian'

It's feeling like the waning days of summer here in Connecticut. Just the other day I took this photo out in a baking campus garden; today it's windy, cool and drizzling. Well, we can use the rain, and it's supposed to be back to heat and humidity by the weekend.

The Mealybug Destroyer

Cryptolaemus feeding on a mealybug infestation on an ice plant (Aptenia).

The common name “Mealybug Destroyer” sounds like it might be part of the advertising for an overhyped, doubtfully effective gardening product, but when applied to the predatory beetle Cryptolaemus montrouzieri, it’s actually appropriate. Here at the University of Connecticut greenhouses, we’ve been trying to minimize the use of pesticides, and rely instead on beneficial insects and other biological controls for pests, as part of an Integrated Pest Management (IPM) program. Cryptolaemus has been critical to our efforts to beat one of the worst enemies of indoor horticulture.

Cryptolaemus is a tropical lady beetle, related to the native and Asian lady beetles commonly found in gardens (and houses) in New England. Adult “crypts” are small, nondescript brown and black beetles, which eat mealybugs and mealybug eggs. Cryptolaemus larvae are what really earn the name Mealybug Destroyer, though. These are camouflaged to look like large, fast moving mealybugs, and they devour pests at a prodigious rate. They mostly go after Citrus Mealybug and Long-tailed Mealybug, but in a pinch they will settle for other insect pests; I’ve seen them make short work of an infestation of Brown Soft Scale, for instance.

Mealybug Destroyers do best in warm, humid conditions, and even in a greenhouse usually don’t survive through the winter. Adult beetles can be ordered through the mail in the spring, from specialist suppliers such as IPM Laboratories. Once a population of crypts gets established, it can quickly become a problem to find enough mealybug-infested plants to keep them fed.

Unfortunately, it is difficult to make use of Cryptolaemus in all but the largest home collections of plants. It’s fairly expensive to acquire a package of the beetles (the joke in the horticulture industry is that IPM stands for “I Pay More”), and you really need a large number of plants with a lot of mealies to support a population of Mealybug Destroyers. The beetles are far more sensitive to pesticide residues than the pests are, and probably won’t survive if systemic insecticides have been applied within the past six months, or possibly longer (pests evolve resistance to chemicals used to control them, but populations of beneficial insects have likely never been exposed to pesticides). Still, under the right circumstances, Cryptolaemus montrouzieri can be a devastatingly effective weapon in the battle against mealybugs.

Newport Flower Show 2010

The Newport Flower Show starts up tomorrow. I was out there bright and early this morning to lend a hand with "passing" entries for the judged show, which basically meant checking for proper naming, making sure no pest-infested or otherwise unsuitable material got through, and filling in paperwork. It was a nice excuse to check out the show setup and a little bit of Newport, and catch up with New England plant people.

The show is held in and around Rosecliff, one of the 19th century mansions along Bellevue Avenue. It's a somewhat fancier venue than the Connecticut Flower Show's Hartford Convention Center.

Massachusetts cactus club bigwig Paul C. and his wife relax on the terrace. It was a hot day, but there was a pleasant sea breeze.

The theme of this year's show was Safari Flora & Fauna, so plants native to Africa were well represented, such as Art S.'s award-winning Aloe plicatilis being wheeled into place here.

Back in the registration tent, the succulent plant entries had all been processed and the action had moved on to cut flowers, so my duties were finished for the day.

Just in time for a late lunch at Rhode Island institution Flo's Clam Shack. The eats at Flo's were pretty typical deep fried seafood, probably a bit fresher and less oily than average for beach food joints.

I meandered down to the beach, but a storm was moving in (possibly remnants of the one that apparently trashed part of Bridgeport earlier in the day), so I decided on a quick retreat back to the safety of northeastern Connecticut.

New York Botanical Garden

On Saturday, about 50 people from southern New England enjoyed a day at the New York Botanical Garden. The Connecticut and Massachusetts cactus clubs chartered a bus for the trip to the Bronx. The weather was fine, and the gardens seemed more spectacular than ever!

The Enid A. Haupt Conservatory, home to a world class collection of exotic plants. The Victoria plants and other tropical water lilies weren't really out yet.

CCSS regular Sully in the New World Desert house, with a Boojum in the background.

The Lithops, Conophytum and other mesemb plants were in a glass case in the Old World Desert house. I think the glass is to prevent visitors from swiping or molesting them.

Theobroma cacao, the chocolate tree. The fruits were all pretty high up.

The Conservatory is slated for major renovations soon, so we got in our trip just in time. In the corners of the palm house there were some recently moved specimens, possibly intended as replacements for some of the old palms that are getting too large.

Cavendishia grandifolia, a blueberry relative in the highland tropical greenhouse. The NYBG has a long history of research in the neotropics (Central and South America), and their living collections from this area are especially good. Nobody else grows some of the plants they grow.

There is a huge area of gardens outside the Conservatory, too. The Rockefeller Rose Garden was just about at its peak.

The rose gardens were completely redone about 20 years ago.

Everyone who knows about carnivorous plants is always aghast at the Sarracenia (North American Pitcher Plants) growing on a seemingly dry slope in the acid-loving plant beds in the rock garden. The plants have persisted there for several years; I suspect the soil below the gravel stays pretty wet.

Trunk of Prunus serrula, the Birch Bark Cherry: the bark looks and feels like ribbon candy.

Hardy cactus expert John Spain admires the rock garden. Next month, the CCSS is meeting at John's house, where he will lead a workshop on making hypertufa troughs like the ones seen here (well, probably they won't turn out quite that nicely, but you can try).

Uncarina grandidieri

Uncarina grandidieri is a small tree with a fat caudiciform base, originally from Madagascar. The eight foot high specimen at UConn flowers profusely every spring as it begins its growing season. During the warmer months, when Uncarina plants are active, they can be treated like tropicals, and watered and fertilized generously. In the winter, they are deciduous, and can be kept nearly dry.

Conophytum bachelorum: the Bachelors’ Cone Plant

Conophytum bachelorum, with fresh leaves in September (the cone-shaped body is a pair of fused leaves containing water-storing tissue).

The whereabouts of Conophytum bachelorum was a long term, vexing mystery for students of mesembs (succulent plants in the family Aizoaceae) and living stones. Discovered in the late 1970s, the distinctively purplish button-like succulent was missing in action for decades, known only from dried herbarium specimens and a single living individual cultivated in England. In 2004, C. bachelorum was rediscovered on an obscure quartzite hill in the sparsely populated northwestern corner of South Africa, and a few seeds eventually made their way to mesemb enthusiasts such as myself.

As with many winter-active South African natives, the seeds germinated and grew strongly when planted in early autumn, and coddled for their early years with bright sun and regular doses of dilute fertilizer in the cool months, and some shade and misting in summer to prevent scorching. Conophytum bachelorum seems to be especially sensitive to summer sunburn, which proved fatal to seedlings in the collections of several experienced growers. In the wild, the plants grow close enough to the coast to experience frequent fog, which may explain how they get by in Namaqualand while having such thin skins.

Conophytum bachelorum in flower in March.

Conophytum bachelorum’s schedule not quite the same as that of the typical Conophytum. The plants flower over an extended period in spring, whereas the overwhelming majority of conos bloom in early autumn. The growing season of C. bachelorum is unusually early, with plants showing a strong tendency to start growing in the waning days of summer if water is available, and to go dormant in late winter (March or even February in the northern hemisphere), weeks or months before most winter-growers fold up shop. As a consequence, the plants flower when they look dormant, covered over by the freshly dried remains of their old leaves.

Young C. bachelorum plants in cultivation, dating from the rediscovery of the wild population, are now flowering and setting seed on a regular basis in several collections around the world. It may be a few more years, but soon enough this neat little succulent should become more generally available.

Miraculotuberum, a New Caudiciform Succulent

Exciting discoveries in the plant world always seem to come from remote mountains in strange and foreign places, such as Canada. It came as a shock to the botanical community when a large and distinctive new caudex-forming succulent plant—Miraculotuberum stopandshopensis—was found right here in the northeastern United States.

Miraculotuberum stopandshopensis in the greenhouse of an anonymous collector.

Miraculotuberum was first collected in 2008, near Nyack, New York, by famed explorer and succulent plant enthusiast Dr. Don Javranos, seen in this video discussing his find. Little is known about the plant’s habitat, and the exact location is being kept secret. Presumably, M. stopandshopensis grows in a temperate desert environment, although desert conditions are uncommon in suburban New York. The plant exhibits several adaptations to life in an arid climate, including an absence of foliage leaves, and a thick waxy coating to prevent desiccation. The spectacular caudex of Miraculotuberum has a bitter taste and sulfurous smell, which deter herbivory by animals and children.

In cultivation, Miraculotuberum is challenging, and plants frequently fail to establish even under the best conditions. Given its northern range, Miraculotuberum is probably winter-hardy, and might make for an interesting addition to an outdoor cactus and succulent bed. Plants are not yet widely available, though they are offered on eBay, where large specimens imported from New York have sparked bidding wars among growers of caudiciform plants, and sold for thousands of dollars. Ironically, it is rumored that ignorant local people in Miraculotuberum’s native habitat sell specimen-size plants to unscrupulous nurserymen for as little as 19 cents per pound.

Signs of Spring

Galanthus nivalis

I caught this clump of snowdrops during the freakishly warm weather last weekend. Temperatures have cooled off since then, but the snowdrops have faded, and a few daffodils located in warm sites are starting to open up.

King Protea

Protea cynaroides or King Protea, the national flower of South Africa, is doing its thing in the UConn greenhouses right now. The flowers (technically flowering shoots composed of many small florets) last for weeks, and there are a couple of additional buds developing, so there should be a nice show for the rest of the spring. The bloom in the photo is the size of a dinner plate. It has a funny sort of chemical smell, not exactly floral but not unpleasant either. The artists among my readership might be reminded of the smell of kneaded eraser.

Nothern greenhouse collections don't seem to include proteas very often, which is a shame. They're not overly difficult in cultivation, and this King Protea flowers every year in Connecticut. I use a nutrient-poor, acidic soil (5 peat moss : 2 perlite : 1 horticultural charcoal), and keep the plants in a very sunny spot in a cool greenhouse. Members of the family Proteaceae are said to be sensitive to excess phosphorous, so it's probably best to fertilize cautiously, using a high-nitrogen formulation.

Marsh Botanic Gardens Hosts the CCSS

Last weekend, the Connecticut Cactus and Succulent Society held their monthly meeting at Yale's Marsh Botanic Gardens. The weather was about as good as it gets in early March, with lots of sun and jacket-free temperatures, and at least 40 people showed up. I was really impressed by the new greenhouses at Marsh, which just opened up last month. The desert plant room wasn't completely finished, but what was there looked great. I'm looking forward to returning sometime to see how they have progressed in filling up all that new space.

The cactus club inspects the new desert collection.

Curator Dave G. also let us tour the old Lord and Burnham greenhouses at Marsh B.G., which are much more cramped than the new facility, as well as being prone to flooding in rainy weather.

Butcher’s Broom: Ruscus aculeatus

Ruscus aculeatus, or Butcher’s Broom, isn’t exactly the showiest plant in the Mediterranean plant collection here at the UConn greenhouses, but it frequently attracts the attention of more observant visitors. Ruscus looks a little like a grayish, knee-high holly bush from a distance, but when examined closely it reveals a puzzling characteristic: its tiny, green flowers and marble-sized red fruits emerge from the middle of what look like its leaves. Normally, we think of flowers growing at the end of stems. Botanical science confirms common impressions about plant morphology in this case; developmentally, it would be just about impossible for a flower to grow directly from a leaf.

The mystery of flower-bearing leaves in Butcher’s Broom is solved when we consider the possibility that those pointy, flat greenish appendages might not be real leaves at all. Indeed, the evidence from detailed study of the position and development of leafy structures in Ruscus indicates that they are really cladodes (sometimes called phylloclades), or flattened, green, leaf-like shoots. The real leaves of Ruscus are reduced to tiny, scale-like remnants, sometimes visible at the base of the cladodes in young shoots. So, Ruscus flowers are borne on stems, just like in any other plant, but the stems have a very unusual form.


Of the half dozen species of Ruscus, R. aculeatus seems to have the spikiest, thickest “leaves,” and is generally the most suitable for growing in collections of succulent plants. It can take soil that dries out completely between waterings, but is also surprisingly tolerant of low light levels. As a houseplant, Ruscus isn’t quite as unkillable as its distant relatives the Snake Plants (Sansevieria), but it still requires persistence and special effort to actually snuff one. Butcher’s Broom can take all sorts of temperature regimes, but does best with cool winters. Growth is always very slow, but a healthy plant will flower and send up new branches from its underground rhizomes when the days are short.

Ruscus aculeatus is not especially common in cultivation, but a few mail order nurseries (such as Plant Delights in North Carolina) do offer it. Florists use other species of Ruscus as “foliage” in arrangements, dry or fresh, though the cut stems can’t be used to start new plants, since they do not root. For those with a truly black thumb, florists sometimes stock fake silk and plastic Ruscus.

Pinguicula lusitanica - the Pale Butterwort

It's the dead of winter here in Connecticut, and Pinguicula lusitanica is looking its best. The biggest rosettes in the photo are only about 2 cm across, but that's about the maximum size for this annual to short-lived perennial carnivore from the western Mediterranean and Atlantic coast of Europe and northern Africa. The cultivation of this funny little butterwort perplexed me, until I realized that it is primarily winter-growing: the plants sulk in hot weather, and the seeds are reluctant to sprout in spring. It's now something of a weed in the carnivore collection out in the temperate greenhouse.

The leaves of Pinguicula lusitanica are distinctive, with edges curled over to the extent that they are almost tubular. The exposed part of the upper leaf surface is covered with hairs, and the sticky glandular trichomes are mostly hidden away under the curled margins (you can see some glandular surfaces exposed on the leaf at 7 o'clock on the rosette at left). Now I'm curious about how the plants trap insects in habitat: do the hairs guide prey into the overhanging part, where they are swamped in mucilage and digested? The traps seem almost pitcher plant-ish.

Help Wanted

A quick heads-up for the plant professionals out there: the University of Connecticut Ecology and Evolutionary Biology Plant Growth Facility is now hiring. This is a full-time position is for a horticulturist specializing in tropical plants. The details are available at the greenhouse website.