Cracking seed germination

Let's put this bluntly; some seeds are just a bitch to germinate.  Once when using morning glories for an experiment, to get good germination all at once, the seeds were washed in concentrated sulfuric acid for a few minutes and then washed in water.  A good deal of the seed coat was dissolved, but the embryos within were undamaged and the seeds all germinated at once.  A lot of our temperate zone seeds need a cold period, often several cold periods, alternating with warmer periods to convince them that spring has sprung and they should germinate.  This is called vernalization.  Some seeds need considerable washing to remove germination inhibitors, a mechanism to assure germination just after sufficient rainfall.  Some prairie seeds actually germinate better after a fire.  In an effort to mimic a fire treatment in a safe and controlled manner, a student researcher took some difficult to germinate seeds (a legume), packaged them in little filter paper packets, constructed a lab-style double boiler, and steamed the packets for 4 mins.  They germinated like crazy after only a 1 week cold period!  Seeds collected from litter after an actual prairie fire also germinated OK, but not quite as well probably because some were cooked and some were not heated enough.  The untreated seed, no fire, no steam, just sat there week after week. The after-a-fire germination is a good strategy too because after a fire  because the accumulated dead plant material is removed so seedlings will get more sun and the ash is full of nutrients.  Now to try the steam heat method on a couple of other very stubborn seeds.   

Botanical questions - grass trees

grass trees living tissues inside them, what is this purpose?? and how are they adapted to fire??

Here’s a recent question (10/27 via comments) submitted to the Phactor, and this is my best effort to answer what seems to be asked. Grass trees are the common name for some yucca-like plants in the genus Xanthorrhoea native to Australia. They grow slowly and can live for 200-500 years. They start out looking like a grassy/yucca-like tuft of stiff-leaves and with time they develop a trunk largely composed of compacted leaf bases, which is very resistant to fire, so they do not burn, although they develop a good black scorching, but insulate the living tissues within from the heat of brush fires. Their habitat is generally open savanna like forests or chapparel, areas subject to occasional or even seasonal burning. The trunk is hollow and the living portions within are adventitious roots that connect the live top to ground (nice picture here). Dead leaves can form a considerable mantle around the stem if the plant has not been subjected to fire. While the outer leaves of the crown get burned the dense whorl protects the growing apex within. They are a great looking plant, and so subject to landscape exploitation much like cacti in the SW USA. My CSIRO colleagues said they did not transplant easily or well. They produce a really distinctive terminal flowering stalk and tough fire-resistant fruits. Fire seems to stimulate seed dispersal and germination.

Joys of Field Work - the most recent chapter

Fire is part of the ecology of grasslands although most residents of the prairie state do not know this because most of the prairie has been converted into the maize and soybean desert. For those of us who study some of the little patches of remaining prairie, fire is an important management tool because it keeps many invasive species, particularly woody plants, in check. So why the hell was my prairie not burned? The excuse was economics and personnel, not enough money, so not enough people to manage the burn. However, since the burning was scheduled the PVC posts that provide an early season marker for locating my study plots were removed leaving only an iron spike driven into the ground and an aluminum ID tag. Because of the particular experimental design these plots, 108 of them across a 6 acre area, were not laid out in a regular grid, but in random groupings of 9. Generally speaking after the fire these tags are not too difficult to find, and after locating 7 or 8 in each group, the remaining ones’ location(s) can then be triangulated. But the prairie was not burned so now all these tags are out there at ground level somewhere in a tangle of last year’s vegetation that easily reached 9-10 feet tall and this year’s new aerial shoots. Finding all the plots is proving next to impossible even with the help of a metal detector and maps of the groups. And metal detectors designed to find a cufflink on a fairway are not so easily used in the jungle of vegetation down there. Think this isn't costing some money and personnel time? Miss by an inch and you won’t see the tag. Oh, yes, the temptation to drop a match and blame it on a passing smoker was very strong.