Monday, June 30, 2008

Amorphophallus Update, June 30

The Corpse Flower has reached 56.5 (144 cm) inches tall, which is an increase of 6.5 inches since Saturday (the last time anyone checked). So, growth is holding steady at a little over three inches per day. That's probably going to be the maximum rate of growth for this bloom, and I'm guessing that growth will taper off in the next day or so. Larger plants have been reported to sustain growth rates around 8 inches (20 cm) per day.

Typically, the growth of A. titanum inflorescences reaches a peak, holds steady for a few days, then decelerates until flowering, with the flower opening about a week after the growth rate starts to decline. So, the smart money is still on Monday, July 7. The blooms open in late afternoon, and reach their peak stinkiness in the wee hours of the next morning. Our past flowers have lasted less than a day in prime condition, with pollen being shed from the male florets and the bloom starting to fold up the day after opening.

Readers in Connecticut might want to check out the local news on NBC 30 tonight: a camera crew was around the greenhouse today, filming the Titan Arum and other points of interest for a segment on things to do at UConn over the summer.

Saturday, June 28, 2008

Friday, June 27, 2008

Amorphophallus Update, June 27

The Titan Arum put on another 3.5 inches, and now stands at 46.5 inches (118 cm) tall.

The smaller, darker bud emerging from the pot just to the left of the pot with the flowering shoot is another A. titanum. It's an immature plant, about eight years old from seed, with a tuber about the size of a cantaloupe. It's nowhere near flowering size, and that bud will undoubtedly expand into a leaf, over the course of the next couple of weeks. The two big plants at UConn are from wild collected seed started in 1994, and first blooming in 2004; the little guy is from seed produced in cultivation at UCSB, on a plant that was a sibling of our mature plants, which began its life here at UConn before heading for the Sunshine State.

Thursday, June 26, 2008

Amorphophallus Update, June 26

The Corpse Flower is starting to enter the realm of "alarmingly large," at 43 inches (109 cm) tall, which is 3.5 inches taller than yesterday. Four inches per day is about the maximum growth rate we've seen on these things at UConn.

Wednesday, June 25, 2008

Amorphophallus Update, June 25

The Corpse Flower grew another 2.5 inches yesterday, and is now 39.5 inches (100 cm) tall. It will probably just about double in height over the next couple of weeks. Since the flowers are borne without foliage (i.e., the leaves are "hysteranthous"), most of that floral mass is coming from stored carbohydrates in the underground corm. Given the history of this plant, those carbohydrates were synthesized way back in summer 2006, the last time the plant had a leaf.

Actually, there isn't quite as much biomass in an A. titanum inflorescence as you might guess. The whole structure is quite spongy, with a lot of air spaces, and the spadix (the central pointy bit) is nearly hollow. Also, this species does grow roots when flowering, so some of the water content of the inflorescence is undoubtedly fresh from the soil. Other Amorphophallus species, like A. konjac, flower when rootless, so even the water in the bloom must be taken from stored reserves.

Tuesday, June 24, 2008

Amorphophallus Update June 24

The bud is 37 inches (94 cm) tall today, or two inches taller than yesterday.

The speckled green sprout behind and to the left of the flower bud is our other mature specimen of Amorphophallus titanum. That plant is behaving normally, sending up a foliage leaf to photosynthesize, after flowering last year. Corpse flowers only produce one leaf at a time, at least as adults: the speckled "trunk" is really a petiole (leaf stalk), bearing a leaf blade dissected into numerous leaflets. The whole thing will collapse into mush when the plant next goes dormant; the only part of the plant that persists long term is the underground corm.

Monday, June 23, 2008

UConn Corpse Flower Redux

Corpse Flower at the UConn Ecology and Evolutionary Biology Greenhouses. Note lens cap on pot rim for scale.

It's official: the larger of the two mature Amorphophallus titanum plants here at the University of Connecticut is going to flower again, after last stinking up the joint Mother's Day weekend 2007. Normally, it takes about three years for a Titan Arum to rebloom. In the usual post-floral sequence, the inflorescence sets any seeds that it is going to set, then withers away, leaving a dormant corm underground. The corm sits for a number of months, then sends up a titanic leaf, which lasts about a year and a half. Then the plant enters another dormant phase before finally flowering again. The plant in the photo was totally dormant for 13 months, and then started sending up what turns out to be a second flower, without an intervening vegetative phase. This is seriously peculiar behavior, and as far as I can tell the first time that two flowers in a row have been observed in an individual of this species.

The corm of this plant weighed 92 pounds after it bloomed in 2007, and no doubt quite a bit more than that before it produced a nearly six foot inflorescence. Possibly, re-flowering is normal--if seldom observed in cultivation--for large Corpse Flowers that do not set seed the first time around (we didn't even try to pollinate it last year, because of worries that producing seed would use up too much of the plant's reserves. Apparently, it still has plenty of reserves). In any case, it will be interesting to see how this year's flowering event plays out.

As of this morning, the inflorescence was 35 inches (90 cm) from soil level to tip. Based on past blooms here at UConn, I'd expect it to open in about two weeks (ca. July 7). Stay tuned for more updates.

Wednesday, June 4, 2008

Curly Bulbs in Springtime

Cyrtanthus species with leaves and fruit, May 2008.

The arid and semi-arid portions of South Africa are home to a tremendous diversity of succulent plants, and also—though it isn’t as widely appreciated—a very diverse flora of geophytes (bulbs and tuberous plants with underground storage organs). Manning, Goldblatt and Snijman, in The Color Encyclopedia of Cape Bulbs (Timber Press, 2002) estimate that there are about 1200 species of geophytes just in the zone of winter rainfall centered around Cape Town. I cultivate a small collection of South African geophytes, and this is generally a pretty dull time of year in that corner of the greenhouse: most are winter growers, and by this point in late spring the winter growers have crashed. There won’t be any sign of life from pots of Lachenalia, Massonia and Cape Eriospermum species until September or October.

A few South African bulbs that I grow come from the eastern parts of the country, where rainfall tends to be heaviest in summer, and these provide a nice change of pace from the brown leaves and withered flowers that dominate the rest of the bulb collection. Possibly the nicest summer bulb I have is the little Cyrtanthus with corkscrew leaves pictured here. I started these plants from seed from Silverhill Seeds, a source that specializes in the flora of South Africa. The material came labeled as Cyrtanthus helicatus, but that doesn’t seem to be a legitimate name.
There are about 57 species of Cyrtanthus, a genus in the amaryllis family (Amaryllidaceae), native to a wide range of habitat types in Sub-Saharan Africa. The species from Silverhill is one from a seasonally dry, summer-rainfall area, and it is leafless and inactive all winter. During the cooler months, the bulbs don’t receive any water at all. It blooms in April, before leaves emerge, with just a single white, amaryllis-like flower per plant, so far as I’ve seen. The leaves always seem to be produced two per bulb per season, giving the plants an amusing double helix look. While the leaves are green, I water the plants whenever the soil surface shows signs of drying out, so that moisture is always available to the roots. Even with diligent watering, the bulbs tend to go dormant before midsummer.

This year, I managed to cross-pollinate several of the Cyrtanthus plants, and the fat seedpods in the photograph are the result. I’ll probably plant the seed as soon as it ripens, since seed of plants in the amaryllis family is often short lived. (Dry, black, papery seeds of the type seen in Cyrtanthus are usually much more forgiving about storage time than the fleshy seeds of some other amaryllids, but better safe than sorry.) At least under my conditions, Cyrtanthus is quick to germinate, but with an awfully long wait for seedlings to reach maturity, even if maturity only means a bulb the size of an olive. I wouldn’t expect the new seedlings to flower before 2013 or so.