Some time ago, I grew clover in flower pots at the office and noticed one day that there were seeds stuck on the window pane. Further observation revealed that

Some time ago, I grew clover in flower pots at the office and noticed one day that there were seeds stuck on the window pane. Further observation revealed that clover flowers used a similar yet opposite mechanism to squirting cucumbers featured in this article. The seed pods would form and then dry out, and the dryness would form a tightness in the seed pod that upon touch(or given enough time and dryness), would burst out propelling its seeds far away from the plant. While some seeds would stick to the window, I can only assume now that this is the seed itself clinging to other surfaced as another propagation method that I've not fully understood. Comparing this experience to the article and the squirting cucumbers, I can imagine that the liquid used in this mechanism would only be useful to heavier seeds, as the added weight would hinder any 'dry' spread process. This is only my immediate thoughts but it seems that evolution and time have figured out this concept long ago! Cool stuff! (edit: typo)