I was able to refine my theory about why the autumn crocus (Herbstzeitlose) appears earlier in some places and later in others. For that I've travelled all of Lobau - from the city limits in the east to the beginning of human settlements in the west, from the danube down south to the lettuce farmers in the north. These photos were taken the day before yesterday:
And these are my conclusions (they're only hypothetical of course, for now):
- The difference in metres above mean Adriatic sea level - as posted earlier - seems to be of hardly any consequence at all. This was prooved to my complete satisfaction by some autumn crocus buds not yet open in the lowest lying region of Lower Lobau, at about 150 metres above sea level, on 28th of august. (Of that I have no photographic evidence because this is the mosquito hellhole and I only managed to snatch about 10-15 apples from my favorite apple tree before I really had to flee, and quick; no time to take a photo, sorry, else those monsters would have eaten me alive.)
- The difference in exposure to the sun seems to make some difference though can't explain everything: the first of today's three photos is one of a specimen growing in full sun, yet it only began to open that day, the 28th. But in other places those exposed to the sun slightly, but not fully were earlier: therefore probably the earliest ones to flower are the ones in half-shadowy places: not too shadowy, and not too exposed to the sun.
- Further the ground they are growing on seems to have an influence; on wetter places (which too are more shadowy ones) with fatter earth the flowering seems to occur later while on poorer earth the flowering seems to happen earlier. On very poor soil autumn crocus do not prosper, that is: on the Hot Lands (Heisslände) they only grow on places half-shadowy which aren't too dry and too poor in soil.
