Yesterday I purchased some native plants for the back yard. Twenty six plants of sixteen species. Nearly all are Tasmanian natives. One exception is the West Australian Hakea elliptica. I didn't read the label. Looking at the leaves I thought I was buying the local species, Hop Bitter-pea, Daviesia latifolia. That may tell you something about my plant ID skills :-) Oh well - I guess the birds will like it.
In any case, I haven't planted them as yet as I've been more interested in what was growing in a couple of the pots alongside the plants. In fact, truth be known, I purchased two Melaleuca ericifoli simply because I was fascinated by the liverworts growing in the pots.
If there are any ....ummm "liverwortologists" :~) out there, please feel free to set me straight my description below.
There are two main categories of liverworts - thalose and leafy. Mine is thalose.
The main leafy looking part of my liverwort is the gametophyte. Gametophytes come in different forms for different species. In this one it takes the form of a thallus. That is to say it has no arrangement of leaves and stems but consists simply of a flat spreading vegetative body.
The tiny white dots on the upper surface of the gametophyte, when examined under my little microscope are actually barrel shaped pores. Some species have simple holes on the surface but these more complex structures suggest my liverwort belongs to the genus Marchantia. The pores lead to little air chambers below the surface that allow for the gaseous exchange needed in photosynthesis.
The underside of the gametophyte is covered in a dense mass hairy looking stuff. These are the rhizoids and their function is to anchor the thallus to the soil.
This liverwort has two means of reproduction, sexual, and asexual. The asexual is the simplest to explain. See the little nodules on the surface. These will develop into little cups (gemma cups) which contain green disc like objects of about half a millimetre in diameter known as gemmae (singular gemma) . If the gemmae are washed out by rain onto suitable soil, a new gametophyte will grow. You can see a gemma in the next photo. This one has been washed down to the underside of the liverwort.
Then there is sexual reproduction. These liverworts are dioceous (They have separate male and female plants) so some of those gametophytes will produce male parts and other will produce female parts.
The long stemmed umbrella like structure seen in photo #. are the archegoniophores (female).
The shorter stalks with the star shapes tops are the antheridiophores (male).
The female receptical (carpocephalum) are initially down near the surface and face up. It is not until after they are fertilised that the stems carry them up high. As the grow taller, sporophytes (where the spore capsules are produced) develop underneath each receptical. The umbrella shaped part grows wider and eventually fold under at the edges so the the spore capsules end up underneath (facing down)
The spores are released and the life cycle continues
Well if nothing else, that was a fascinating diversion from planting my newly acquired plants.
- Australian Bryophytes Web Site . 2008. - Australian National Botanic Gardens/Australian National Herbarium
- Biology 7th Edition - Villee, Claude. 1977. - Saunders