Laudator Temporis Acti

Frederick Goddard Tuckerman, Sonnets, Part II, Number XXIX, from Poems (Boston: Ticknor and Fields, 1864), p. 227:

How oft in schoolboy-days, from the school's sway
Have I run forth to Nature as to a friend,–
With some pretext of o'erwrought sight, to spend
My school-time in green meadows far away!
Careless of summoning bell, or clocks that strike,
I marked with flowers the minutes of my day:
For still the eye that shrank from hated hours,
Dazzled with decimal and dividend,
Knew each bleached alder-root that plashed across
The bubbling brook, and every mass of moss;
Could tell the month, too, by the vervain-spike,–
How far the ring of purple tiny flowers
Had climbed; just starting, may-be, with the May,
Half-high, or tapering off at Summer's end.

Tuckerman suffered from poor eyesight ("with some pretext of o'erwrought sight") all his life. There is a parallel to telling time by the growth of the vervain-spike in Henry David Thoreau, Journal (August 21, 1851):

Bigelow, speaking of the spikes of the blue vervain (Verbena hastata), says, "The flowering commences at their base and is long in reaching their summit." I perceive that only one circle of buds, about half a dozen, blossoms at a time, — and there are about thirty circles in the space of three inches, — while the next circle of buds above at the same time shows the blue. Thus this triumphant blossoming circle travels upward, driving the remaining buds off into space. I think it was the 16th of July when I first noticed them (on another plant), and now they are all within about half an inch of the top of the spikes. Yet the blossoms have got no nearer the top on long [sic] spikes, which had many buds, than on short ones only an inch long. Perhaps the blossoming commenced enough earlier on the long ones to make up for the difference in length. It is very pleasant to measure the progress of the season by this and similar clocks. So you get, not the absolute time, but the true time of the season.

Bigelow is Jacob Bigelow, Florula Bostoniensis: A Collection of Plants of Boston and Its Vicinity, with Their Generic and Specific Characters, Principal Synonyms, Descriptions, Places of Growth, and Time of Flowering, and Occasional Remarks, 3rd ed. (Boston: Little and Brown, 1840), p. 254.

See also Thoreau's Journal (August 22, 1859):

The circles of the blue vervain flowers, now risen near to the top, show how far advanced the season is.

Verbena hastata (photograph by Albert F.W. Vick)