The Weedy Introduced Geraniums

I remember that, when I was little, I loved to look at springtime weeds-- especially the introduced annual Geraniums that are the subject of this post-- assigning my own common names to them and trying to find interesting variants. Among these Geraniums there's quite a diversity of leaf shapes, with the "Cutleaf" G. dissectum at one end, the staidly normal-geranium-looking G. pusillum in the middle, and G. molle rounding out the other end with its rotund leaves with little space between the lobes.

G. dissectum. Taller than its brethren, dissectum's flowers are some permutation of saturated carmine pink.

G. pusillum, in pale pink, approaching white.

Note that, as always, my IDs may be imperfect, and there are other introduced annual geranium species of wide distribution.

The flowers are what one would expect, small versions of the "civilized" varieties of cranesbill and the native perennial sorts. I suppose their size is an adaptation to the relatively ephemeral life cycle of these plants, facilitating speedy reproduction while requiring little energy expenditure. Their seed capsules have the classic cranesbill shape.

A blurb on Wikipedia-- without citation-- claims that G. carolinianum tolerates relatively alkaline soil conditions, which could very well be the case, given these plants' predilection to spring up among concrete rubble, gravel, and other limey substrates.

My affection for weeds crops up again-- they might be promiscuous aliens, but I think the introduced annual geraniums are charming.