in Thoreau’s Journal:
I did not see but the seeds of milkweed would be borne many hundred miles––and those which were ripened in New England might plant themselves in Pennsylvania. Packed in a little oblong chest––armed with soft downy prickles & lined with a smooth silky lining––lie some hundred of pear shaped seeds or shaped like the weight of steel-yards––the plumb. Closely packed and filling the follicle one or 2 hundred seeds––which have derived their nutriment through a band of extremely fine silken threads attached by their extremities to the core. At length when the seeds are matured & cease to require nourishment form the plant––being weaned & the pod with dryness & frost bursting––the extremities of the silken threads detach them selves from the core & from being the conduits of nutriment to the seed become the buoyant balloon which like some spiders’ webs bears the seeds to new & distant fields. They merely serve to buoy up the full fed seed.–– far finer than the finest thread. Think of the great variety of balloons which are buoyed up by similar means. I am interested in the fate or success of every such venture which the autumn sends forth.