De Magnetica [...] Plantarum p. 643

but when the sun rises it regains its vigour, and the more the sun burns the greener it becomes, and all day and all year it turns its leaves to the sun. I believe this to be the same herb of which I read in the Arab Salamas, in the book which he entitles Bostan Alduni, that is 'the garden of the universe', which, as if endowed with some power of sensation, shrinks from the toucher's hand, but when touched shrivels, and which he also says to have some wonderful concord with the sun, such that it goes to bed when the sun does, rises when it rises, sinks when it sinks, a true mimic of the sun in every respect. To this amazing flower our heliotropes in some way correspond. For in addition to those already mentioned, Mallow flowers also, when the sun is at its noon, open up as if gaping at the brightness of the star, and at the other hour they pine as if for its departure and for longing, and close up; which is why Theophrastus calls it 'of an hour' [horaria], and Columella sings of the Moloche [Mallow]:

And Moloche, who follows the sun with bowed head.

It really is a prodigious miracle of nature that on a cloudy day herbs should betray the hiding sun and, even with a cloud in the way, like course-markers show by the arrangement of their leaves the concealed star's true position and rotation; or rather that they should stand in for a sundial so well that we can tell the hours when the sun is not out. There is also a sort of spurge [Tithymallus, Euphorbia] found here with us which they not inappropriately call 'helioscopon' [sun-gazer]; it follows the sun's journey, and always continues with it with bowed head till it sets; and during the day it always leans toward it, so that sometimes it seems to have twisted its stem, such is its eagerness to follow the star. Prosper Alpinus (Egyptian Plants ch. 10) says the same about the tamarind of Ethiopia and Arabia; these are his words: The tamarind, which they call Derelside, is a tree the size of a plum, densely branched, with the leaves of a myrtle; it bears flowers very similar to orange blossom from the middle of which come four very slender white threads, from which thick pods are produced, at first green, then of a mature greyness. Inside they contain a few thick seeds, uneven and hard, and a sour-tasting black pulp. In Egypt these trees are not very common, and are not native, as they are brought there from Arabia Felix and Ethiopia, and are kept in orchards. It is considered something of a miracle that one tree is said to live in the desert of Saint Macarius, near the Monastery of the Assyrians, in which soil no other kind of plant lives. The remarkable thing about this plant is that its leaves always follow the sun, and are called Sunseekers. For when it