Growing some haploid ferns

Today's task is to have students start growing some haploid ferns.  Your familiar ferns are diploids and they are asexual producing spores.  Novices often think they have spores but really they have sporangia, which have 128, 256, or 512 spores, there abouts, in them.  They are looking for something small, but they don't realize how small.  If you want to do this yourselves, here's how.  Find a fern with mature sporangia.  The sori, clusters of sporangia, usually look brown at this stage. Take two pieces of white paper.  Fold one into corners and crease it, then flatten the paper back out.  Place the fern frond on the paper sporangia side down.  Cover with the other piece of paper and leave it over night.  As the specimen dries out, the spores are shed onto the paper; look for brownish dust.  The creases make it easy to gather the spores by tapping the paper.  Go to a local garden store and buy a Jiffy 7; they cost about 15 cents.  It's a little compressed pellet of peaty soil in a little mesh bag.  Soak it in water overnight and it will expand.  Get a wide mouth pint canning jar, or an empty peanut butter jar, or something similar.  Turn it upside down and place the Jiffy 7, now more like a Jiffy 42 on the lid to produce a growth chamber terrarium.  Tap spores sparsely onto the surface of the Jiffy 7.  Cover with the jar, screw into the lid and place in a north window.  You don't want direct sunlight, so you also could place it back a ways from a brighter window.  A couple of weeks later you should see green growth.  It's OK to take them out to examine them, and should they need a bit of water place the Jiffy 7 in some shallow water for a few minutes, then return it to its growth chamber.  In 2 months you should have flat haploid ferns about the size of your little finger nail; they are actually called a gametophyte thallus, but it's still a fern, just haploid.  This is the sexual stage of the fern.  A mist of water will cause mature antheridia to release sperm and should a mature egg be around, fertilization will occur and a bit later you'll see the first frond of a diploid fern appear (the familiar phase).  With some patience this can will grow to maturity. 

Bryophyte Week - Hornworts

Dr. Chips upped the ante in his comment to yesterday's bryophyte blog; he's seen and recognized a hornwort in the field! Take that my fellow naturalists. Only one genus (Anthocercos) is mentioned or illustrated in most textbooks, even ones on plant diversity, but there are 5 more genera, or if you really dwell on minutia, up to eleven genera in all. Basically the problem is that hornworts are small and they tend to grow in wet and very dimly lit conditions, and how often do you go looking around in such places? With a thin, rather irregular ribbony thallus they closely resemble liverworts and the gametophytes of some ferns. The only really distinctive feature readily seen without a microscope is the columnar sporophytes (the "horns"), which are the diploid generation. For the most part these sporophytes are dependent upon the maternal gametophyte, but under certain conditions the sporophyte can persist as a free-growing organism after the maternal gametophyte dies. In terms of complexity, the gametophyte is hardly more complex than some green algae, and indeed it has only 1 chloroplast per cell, a very algal character. So let's get out there, down on your hands and knees, and scout for a new genus to add to your plant diversity life list. Image credit: U. Hawaii.

Bryophyte Week - Haploid Holiday

Last week's blizzard day generated a laboratory crunch this week. Even in a survey type class, it takes more than a three-hour laboratory period to cover bryophytes. Typical, bryophytes just get no respect. So the rest of the morning will be spent rounding up the live specimens from the greenhouse so that they may be tortured all afternoon. As always Riccia seems to be missing. It always seems to get rediscovered, but usually too late. However you can always count on the marchantioid liverworts. Here's a nice image of one from the field showing the broad (~1 cm) ribbon-like thallus. The photosynthetic chambers each with a central pore are nicely evident, as is the dichotomous branching. Liversworts are quite uncommon anywhere in the maize and soybean desert; this image is from Washington near the home of the infamous Dr. Chips, who lurks around this blog from time to time. Like all bryophytes, and unlike all other land plants, the organism is haploid so that 2nd set of chromosomes is so over rated.

Ever seen a fern this pretty?

Here's a pretty image of a fern. Have you ever seen a fern like this one? No question about it, this fern is pretty small, about the same size as a neatly trimmed nail on your little finger, and at that size, a fern can be over looked pretty easily.

You may think that this fern doesn't look very fern-like, but in this you are wrong. Your experience with ferns is just too limited. Granted this fern has no ferny fronds, and no vascular tissue either, but I assure you it is quite typical. The most interesting thing about this fern is that it is haploid. The nucleus in each of its cells has only a single set of chromosomes. All of the ferns with which you are familiar have two sets of chromosomes. And what a difference this makes.

This haploid fern is the sexual phase of its life cycle. It makes sex cells, eggs and sperm, and after fertilization, it nutures, for a short while, an embryonic fern, which can grow into a typical appearing fern. So this haploid fern is not some strange, exotic beast, but just the alternate phase of the fern life cycle, the gametophyte phase, the gamete (sex cell) producing plant. Like all other vascular land plants, the familiar fern is the diploid phase, the sporophyte phase, the spore producing plant. And with that I am off to sow some spores and raise some haploid ferns.