Of the mechanical action of plants

XLVI.  In their effect upon plants such natural forces as I have mentioned produce some curious mechanical results.  Thus it is possible to determine the time of the year from the motion of the leaves of certain trees like the olive, the white poplar and the willow, for when the summer solstice has arrived their leaves turn over.  Not less curious is the habit of that flower which is called the heliotrope, which in the morning looks upon the rising sun and, following its journey to its setting, never turns away its face.

Of the protection of nurseries and meadows

XLVII.  Those plants, which, like olives and figs, are grown in the nursery from cuttings and are of a tender nature, should be protected by sheds built of two planks fastened at each end:  moreover they should be weeded, and this should be done while the weeds are still young, for after they have become dry they offer resistance, and more readily break off in your hand than yield to your pull.  On the other hand the grass which springs in the meadows and gives you hope of forage not only should not be rooted out while it is growing, but should not even be walked upon; hence both the flock and the herd should be excluded from the meadow at this time and even man himself should keep away, for grass disappears under the foot and the track soon becomes a path.

Of the structure of a wheat plant

XLVIII.  A corn plant consists of a culm bearing at its head a spike, which, when it is not mutilated, has, as in barley and wheat, three parts, namely:  the grain, the glume and the beard, not to speak of the sheath which contains the spike while it is being formed.  The grain is that solid interior part of the spike, the glume is its hull and the beard those long thin needles which grow out of the glume.  Thus as the glume is the pontifical robe of the grain, the beard is its apex.  The beard and the grain are well known to almost every one, but the glume to very few:  indeed I know only one book in which it is mentioned, the translation which Ennius made of the verses of Evhemerus.  The etymology of the word gluma seems to be from glubere, to strip, because the grain must be stripped from this hull:  and by a like derivation the hull of the fig which we eat is called a glume.  The beard we call arista because it is the first part of the corn to dry (arescere), while we call the grain granum from the fact that it is produced (gerere), for we plant corn to produce grain, not glumes or beards, just as vines are planted to produce grapes, not tendrils.  The spike, which, by tradition, the country people call speca, seems to get its name from spes, hope.  For men plant with hope of the harvest.  A spike which has no beard is called polled (muticus), for, when the spike is first forming, the beard, like the horns of a young animal, is not apparent but lies hid like a sword in its scabbard under a wrapping of foliage which hence is called the sheath.  When the spike is mature its taper end above the grain is called the frit, while that below, where the spike joins the straw culm, is called the urruncum.