Gneater (neater) than all get out!

Visits to our teaching greenhouse still manage to deliver surprises even thought I have been doing it regularly for years.

This is something the Phactor had never seen before: the ovulate strobilus (cone) of Gnetum (knee-tum). Hmm, that's pretty funny, telling you how to pronouce a silent G with a silent K.

Gnetum is a tropical liana, and that's one of the reasons I've never seen strobili before. They're usually way, up, there. The closest I've come before is the seeds, mature ovules, which are about 4 cm long. They have a fleshy, reddish outer seed coat that attract and reward an animal disperser. Finding these seeds on the rain forest floor means that somewhere far above where the vine clamors along in the canopy, a strobilus just like the one above got pollinated.


The strobilus consists of several whorls of small bracts (modified leaves) above which is a whorl of ovules. Ovules are not eggs so their name is a misnomer. Ovules are jacketed, indehiscent megasporangia. The single megaspore produced develops into a haploid female (a gametophyte) who then produces an egg. The jacket prevents the pollen access except through a small hole. The ovules shown here are ready to receive pollen. The ovule has exuded a a drop of sticky liquid out through this small opening and any pollen grains (endosporic males) that adher to the surface of this pollen drop get pulled inside the ovule when the ovule reabsorbs the liquid.

This is not the work of a passive female. She reaches out, grabs passing males, and pulls them into her lair.

Now if the foregoing description wasn't a tipoff, what makes Gnetum so Gneat is that this is a gymnosperm, a relative of conifers, albeit a fairly distant one. Yet as you can see, this vine has broad leaves, and it has vessel elements in its wood, both features usually associated with flowering plants. And of course there is a certain flower like quality to the strobilus.

Do flowering plants share a common ancestry with Gnetum? The jury is still out. For many years data suggested that the answer might be yes, but most recent studies suggest this strange plant is more closely related to conifers, and not in a gymnosperm lineage having a common ancestry with flowering plants.

Flushed with success

Regular visits to our teaching greenhouse are part of my job and mental health program. Although the facility is not physically impressive, the number and variety of plants contained therein is quite impressive. Interesting observations of exotic plants happen regularly.

Over 20 years ago I brought a small tropical tree seedling back from Queensland Australia. It’s the genus Maniltoa in the legume (bean) family and it now has nearly outgrown the greenhouse. If it were not pushing up against the greenhouse glass this tree’s limbs and leaves would show a graceful arching. But this plant has a most unusual and ornamental feature. It produces huge buds from which emerge whole branches bearing nearly full-sized leaves, but here’s the strange part, these branches and their leaves are pink and totally limp. They dangle down like rags, and since the tree tends to flush, a number of such pink branches emerge from buds all at once. Such flushes of new vegetation are thought to overwhelm herbivores that might attack the new foliage.

Slowly, over a couple of weeks, the pink pigments fade and chlorophyll slowly develops turning the leaves pale green. And then, over another few weeks, the branches and leaves slowly pull themselves up into a rather graceful arch. They accomplish this by having a specialized swollen zone called a pulvinus at the base of leaflets, leaves, and branches. Looking and acting a bit like a knuckle, the pulvinus (see close up on right) reorients the branches and leaves. The same structures close up and droop many legume leaves at night and account for the movement of leaves on the touch sensitive Mimosa pucida, another legume.

So our Maniltoa has provided us with a bit of colorful tropical cheer on a cold, late winter day. Enjoy.

Tropical biology dreaming

It's a Monday, the first day of the semester, and the coldest day of the year, a near triple convergence to generate depression. Actually the coldest day of the year is predicted for a bit later this week (a low of -13F). Damn that cheap imported Canadian weather. Still the winter weather depresses me almost as much as politics here in Lincolnland.

Although I often look forwad to the beginning of new semesters, I loath the reports and other paper work that entails. Where's my personal assistant, and why haven't they taken care of all this crap? I don't mind the students, or teaching my classes (although my dislike of exams grows with each year), but why so I have to do it in Lincolnland? After all where should a tropical biologist be but in the tropics?

So I'll post a picture of where I want to be this semester, and I'm willing to bet that my students, if price were not an object, would join me there to a person. So here it is, a pictoral tribute to tropical biology. This particular location is Mission Beach in far northern Queensland. Although beautiful, the tropics are not completely idyllic. There are a few things you should know about this location. One, salt-water crocs have been known to walk right down the beach, and to them, you are prey. Two, seasonally the box jelly fish migrates out of the mangroves and float around in this still tropical water inside the Great Barrier Reef. Getting stung by a box jelly is not a life experience anyone recommends. Still you can get yourself a Castlemain XXXX Bitter ale and sit in the shade of the coconut palms lining the high water mark and think great thoughts about the tropical biology. If you walk a little ways you can see parasol palms and even cassowary if you are lucky and quiet.

So why can't I take my class on a field trip? After all we have students who travel far and wide to hit, kick, carry, or throw a ball, yet no resources exist for similarly educating biology students. Hmm, that's another depressing thought. Better stop while I'm ahead.