Signs of healthy garden

It was a busy gardening week, lots of shrubs to clip back, lots of leaves to clean up, lots of planting and moving (new location for kitchen garden).  And halfway decent weather too.  One sign that we have a healthy garden is how many desirable plants are reproducing.  Bloodroot is suddenly popping up all over, sometimes in amusing places.  Ramp seedlings are also appearing in lots of places (are the fruits/seeds ant dispersed?)  Trillium grandiflora and Hepatica acutiloba  have both produced seedlings, and we take that as a good thing.  Now here's another sign.  While cutting back a Kerria shrub (lots of winter die-back), TPP collected these poking up through the leaf mulch.  Oh, did they make a delectable sauce.  These are the black morel (Morchella angusticeps) and in another location a volunteer orchid (as yet not identified with certainty (missed the flowers)) is returning for another season.  Organisms just keep finding our gardens.  Mostly this makes us happy.

Birth of a lichen

Lichens are symbiotic organisms consisting of a highly organized fungal mycelium enclosing algal cells. What's strange about lichens is that without the algae, the fungus just looks like a fungus. Without the fungus, the algae is just algae. They only take on the form recognized as a lichen when the two organisms are in that symbiotic association, and of course, the term itself means "living together". This presents some interesting aspects of reproduction. This illustration is from the November 2014 issue of the American Journal of Botany.  The sexual reproduction of the lichen is fungal in nature, so to form a new lichen, the fungus must capture a compatible algal cell anew.  This illustration shows this very early stage where fungal hyphae (filaments) have found and encircled an algae cell. The proliferation of the hyphae and the division of the algal cell is a demonstration that the symbiotic interaction, the lichenization, has begun. The accompanying article by William Sanders provides illustrated diagrams of the sexual and asexual reproductive cycles of lichens, all very nicely done.

Massive simultaneous algal orgy

Sex is always a good topic although mostly people have the wrong idea. From the biological perspective sex is production of genetically diverse offspring via mating. Most organisms, which are mostly unicellular, reproduce asexually, so all their offspring are genetically identical, a clone. And this works so well and so efficiently that sex among some organisms is a rare event in nature, so when biologists witness one, they get excited, intellectually.
In this instance the organisms are two species of diatoms, unicellular algae that are phytoplankton, the grass of the oceans. Diatoms are pretty nifty because their cell wall is made of glass, in two halves that overlap each other rather like a petri dish. This poses a bit a biological problem because a cell cannot bend or stretch a glass cell wall so when the cell reaches a certain maximum size for its cell wall the cell divides, which is how it reproduces asexually. The two daughter cells each inherit one-half of their progenator's cell wall, and synthesizes a new inner half. This means one of the two can grow as large as the original cell, but the other having inherited the slightly smaller inner half, so it's maximum size is constrained and it becomes a bit smaller.
Now think forward. When each of these two cells divide, the larger of the two produces two daughter cells just like the two described. But when the other daughter cell divides the biggest one daughter can get is the slightly reduced size of the maternal cell, but the other receiving the inner half of the cell wall is smaller yet. Now let's do this thousands of times. Some diatoms will still be as big as the original cell, but lots of lineages were getting smaller and smaller. At some point the smaller cell size triggers sexual reproduction where the smaller cells divide into gametes, sex cells, which escape their glass prison, fuse with a suitable mate, forming a new cell that enlarges to an optimal maximum size for a diatom, synthesizes a new cell wall and starts the whole process all over again.
The environment plays a role in such events because you don't want to be the only organism at an orgy to release your gametes into the big broad ocean. So what happened here was some environmental event triggered sexual reproduction in two species of diatom simultaneously, and someone was there to watch (record some data).
Whew! Sort of gets you all sweaty just thinking about it.

Aphids driving us buggy

Here in Lincolnland we live in the midst of the maize and soybean desert, so some side affects can be expected. Presently gazillions of aphids have descended upon us and their swarms shimmer annoyingly in the evening rays of sun as autumn advances. Swarms of aphids are so thick you can hardly breath, and please, do not ask a bicyclist to smile. Spider webs are filled with little tidbits, and the swordtails in my fountain pond are feasting upon thousands of aphids. These are not just any aphids, but soybean aphids, and this winged stage is seeking a tree upon which to mate and lay eggs for over wintering. But they are not just seeking any tree, but a buckthorn (Rhamnus), not exactly a common tree. One of my colleagues tracked down a buckthorn yesterday and its leaves were a mass of aphids, so there is precious little room at the inn for all those gazillions still looking. This massive population built up during favorable summer weather (cool, wet) will crash. But here's the amazing thing about such insects. The offspring of those few aphids (in comparison to the whole population) will disperse next spring seeking soybeans, and if favorable conditions prevail, their ability to reproduce could again produce such massive populations. If soybean aphids pose an agricultural problem, then perhaps buckthorn eradication will be proposed to break their life cycle, just as currants and gooseberries were eradicated to break the life cycle of white pine blister rust. In the meantime, these aphids are attracted to yellow and light green, so dress accordingly.