Ginkgo from Seed

A few years back in October, on a trip to Japan, I picked up half a dozen Ginkgo biloba seeds that had fallen around a huge old tree at Washinomiya Shrine in Saitama. I cleaned off the pulpy, foul-smelling outer seed coats, and stuck the seeds in a plastic bag to keep them moist for the trip home. Ginkgo seeds don't remain viable if they dry out too far, and also don't germinate much at all unless they receive slightly unusual treatment.

Once back in Connecticut, I planted the Ginkgo seeds in a loose, airy soil mix, not more than a centimeter deep. The embryos inside develop for some time after they are detached from their mother tree, so Ginkgo seed pots should be kept warm and moist for a month after sowing. After their warm period, the pot went to the refrigerator for two months of stratification, a period of cold (but not quite freezing) and damp conditions that many temperate-climate plants need for proper germination. In early spring, I moved the pot out to the greenhouse, and after a fairly long wait, eventually got three healthy seedlings.

Ginkgo seedlings quickly develop a robust tap root, even while the above ground shoot is small and spindly, so I separated out the young plants early on and put them in relatively large, deep pots. All three seedlings survived and are now well-branched and waist-high. There are interesting variations in Ginkgo leaf shape and size, and the Washinomiya trees have leaves that are more deeply bilobed than the "American" Ginkgoes growing next to them in the greenhouse, derived from seeds from UConn campus trees. The three seedlings from Japan are also noticeably different from each other, with the one in the foreground in the autumn photo below having very large but classically-shaped Ginkgo biloba leaves, while a shorter plant visible in the background has small, deeply lobed and tattered leaves.

For now, the new Ginkgoes are staying in the cool greenhouse in pots, for display and use in class demonstrations. Possibly they would like to be planted out in the ground at some point, if a good spot can be found for them.

Hot Stuff

'Bhut Jolokia' or Ghost Pepper was long considered the hottest pepper in the world.

Frost has been late to arrive this fall, but the hot pepper season out in the garden is not going to last much longer. This year I experimented with growing some of the very hottest Capsicum cultivars, and using them very cautiously to spice up sauces, stir-fries and burritos.

'Bhut Jolokia' is a hybrid of Capsicum chinense that was originally cultivated in the northeastern corner of India. The ancestors of all of the chili peppers and bell peppers came from South America, but were spread to the Old World rapidly after European contact, allowing time for many unique new varieties to be selected, especially in southern Asia.

'Bhut Jolokia' rates at about one million Scoville units, at least when grown under ideal warm and sunny conditions. Ghost Peppers from Connecticut are probably not that potent, but a few finger-nail slivers of fruit are still plenty to make a dinner that's about as hot as I can tolerate. Scoville units are a measure of dilution needed before a human taster would not be able to detect any heat, i.e., a gallon of pureed 'Bhut Jolokia' would need to be diluted in a million gallons of water to make a more or less non-spicy solution. For comparison, Jalapeño peppers rate at less than 10,000 Scoville units.

7-Pot Yellow Chili.

From the Caribbean come several strains of hot pepper known as '7-Pot' chili, so called because one pepper is enough to season seven pots of stew. Here in New England a yellow variety grew pretty slowly and set fruit late, though a couple of plants are still going to yield more than enough peppers to spice up my stews for the foreseeable future. '7-Pot' varieties have similar Scoville ratings to 'Bhut Jolokia.'

'Trinidad Scorpion Moruga Blend'

'Trinidad Scorpion' is another land race (localized, traditional variety) of chili pepper from the Caribbean. The selection 'Trinidad Scorpion Moruga Blend' tested out last year as the hottest pepper ever recorded, at 1.5 to two million Scoville units. Some new hybrids are supposedly even hotter, though any of the three varieties pictured here exist in the murky borderland between foodstuff and biochemical weapon, and demand significant caution when handling. I made some Trinidad Scorpion hot sauce (6 de-seeded fruits diluted in a cup of vinegar, a cup of cooked apples and carrots and 2 teaspoons salt), and just about had to flee the kitchen when it was cooking, even with exhaust fans going full blast. After a couple of weeks of soaking, rinses with alcohol and runs in the dishwasher, I think the food processor is decontaminated. The sauce is actually kind of nice (Trinidad Scorpions have a pleasant fruity-floral flavor under all the heat), if used a drop or two at a time.

NECPS Annual Show

Sarracenia alata, the Pale Pitcher Plant, cultivated from a collection from Covington, Louisiana.

The New England Carnivorous Plant Society is having its 10th annual show this weekend, at Roger Williams Park in Providence. It's a nice time of year for the summer-active carnivores like Sarracenia especially; they've spent the season outdoors soaking up the sun and rain and catching insects, and are at their peak before their October decline into a winter torpor. It's always kind of amazing to see what carnivorous plant fanatics are growing in backyards, windowsills and greenhouses throughout New England, all concentrated in one spot. I suspect that this is pretty much the best show of its kind in the U.S.

More information is on the NECPS website.

Welwitschia Propagation

Female Welwitschia in cultivation at the University of Connecticut, mid-July. Note the pollination drops of sugary liquid at the tips of filaments protruding from between the cone scales.

Welwitschia mirabilis is a distant relative of the conifers, native to the Namib desert in Namibia and Angola. Welwitschia is notable for a number of reasons, most obviously its fat, stumpy trunk and the single pair of strap-like leaves that last for as long as the plant survives, which is thought to be up to 1000 years or possibly more. The trunk of a Welwitschia never produces branches (aside from ephemeral reproductive shoots) or offsets, and the only way to propagate the plants is by seed.

Welwitschia matures at around 10 years old under my conditions, although if given a more generous root run and warmer temperatures they can grow considerably more quickly. Adult plants are either male or female. From my observations, male plants seem to be more common than females, but that's based on a small sample size, and I haven't run across any surveys of sex ratios in the wild. In both cultivation and their southern hemisphere native range, Welwitschia cones are initiated in the spring and become fully formed and receptive in mid-summer.

Male Welwitschia with pollen-producing cones. Male cones are smaller that the females, only a little larger in diameter than a pencil.

Welwitschia seems to be pollinated by insects and not by wind, which is somewhat unusual for a cone-bearing plant. During the early afternoon the female cones secrete a drop of nectar from whisker-like extensions of their ovules. The male cones bear little whorls of pollen-producing microsporangia, and at the center of each whorl is a nectar gland, which may itself be a modified, vestigial ovule. The cones of cultivated plants in Connecticut attract a variety of insects collecting nectar and pollen, including flies, wasps, bumblebees and yellow jackets. In Namibia, various flies (including the common housefly, which also shows up on my greenhouse plants), bees and wasps have been observed transferring pollen from male to female plants. Neither wind-dispersed pollen nor the Welwitschia Bug (Probergrothius sexpunctatis), both of which were once suspected of being important to Welwitschia reproduction, actually seem to be involved in pollination of plants in the field (Wetschnig and Depisch, 1999).

A large wasp visiting male cones on a cultivated Welwitschia.

Successfully pollinated female cones ripen in autumn, about two months after pollination. Ripe cones shatter into a pile of papery scales and winged seeds, which seem to be adapted to wind dispersal.

Female cones in September releasing winged seeds.

I've had good luck sowing the seed right after it was shed, in September or October, in a sunny, warm spot, in a pot of well-drained soil mix for desert plants. I mostly use biodegradable fiber pots, which can be sunk into the soil of a larger pot when the seedling needs more room, minimizing root disturbance. The seed germinates well within a few weeks in moist soil. The young seedlings are very susceptible to damping off, for some reason; once they make it past their first few months they seem to become resistant to such problems. I've tried the usual cultural remedies for damping off--strong sun, allowing the soil surface to dry as much as possible--without much success, and will probably resort to the use of a fungicide the next time I sow a batch of Welwitschia.

Welwitschia seedling at a few days old. The cotyledons (seedling leaves) start out a bronzy-yellow color, and take some time to turn green.

Welwitschia seedling at age six months, with its first and only pair of true leaves emerging at right angles to the cotyledons.

Reference: Wetschnig, W. and  B. Depisch. 1999. Pollination biology of Welwitschia mirabilis Hook. f. (Welwitschiaceae, Gnetopsida). Phyton 39: 167-183.

Corpse Flower 2013

For the third summer in a row, the University of Connecticut greenhouses are going to have a flowering Amorphophallus titanum. The inflorescence has been shooting up at about 10 cm per day since it broke out of its bud scales last week, and is now 117 cm tall. The rate of growth has slowed a little bit recently and the inside of the spathe is developing some reddish color, so I suspect we'll see an open bloom in less than a week's time.

Long term readers will recall that previous Titan Arums here at UConn have had yellow spadices; this plant will be the first that I've seen in person with a purple spadix. The current inflorescence is from a different batch of seed than the previous flowerings, which were grown from seed collected in Sumatra in 1994. This one is only about 10 years old, and was started from seed produced by cross-pollinating plants from the 1990s cohort grown in California. The plant's mother actually germinated here at UConn, so the father was possibly a purple form, or our original plants were actually a mix of the purple and yellow color morphs, and it was a matter of chance that the two plants kept here at UConn happened to be the yellow form. Or possibly purple is recessive and can turn up in crosses of two yellow plants; I'm not sure how spadix color is inherited in A. titanum. In any event it will be an interesting change to have a purple-spadix plant in flower.

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 Edited to add: This year's Corpse Flower was kind of a flop. Nine days after the photo above, the spathe did pull back a bit and there was some odor, but it never really fully opened. Possibly, this young plant was still too small to properly sustain a bloom. The other mature plant of A. titanum at UConn is sending up a leaf, though, and I hope that it has a nice long growing period to bulk up its tuber and put on a proper flowering event in 2015 or so.