In Egypt, near the Pyramids, one often finds _Carlina acaulis_, a little thistle which has no stem, but is merely a flower seated in the middle of a rosette of leaves which lie flat on the sand. In the centre there is a circle of sharp spines, each of which is from one to two inches in length. The nostril of a hungry camel or donkey is sure to be pierced if it tries to eat the leaves. The spines of this thistle, like those of our Carline and the _Centaurea calcitrapa_ (thistle of the Bible), spring from the bracts surrounding the flower. The ancient "calthrops" or "crawtaes" (first used by the Romans) were designed from the spines of the last-named plant[88] (_calx_, heel, and _trappa_, snare.) It had four iron spines, so that, however it was thrown down on the ground or in a ford, a spine was sure to stick up and to lame man or horse. [88] Ridley _l.c._ [Illustration: 1. Old Roman Calthrops, left on roads, fords, etc., to lame horses. 2, 3. Fruits of Tribulus, showing efficient spines. Animals' feet, in passing, must catch them. They are more efficient than Calthrops.] The Tragacanth plant has also very neat spines. They are the persistent spiny stalks or midribs of the older leaves from which the leaflets have dropped away. The fresh green leaflets are quite protected inside these withered spines. Several grasses have leaves which end in sharp or needlelike points. One of these, _Festuca alpestris_, actually produces bleeding at the nostrils of grazing cattle, and is detested by all the shepherds of the Alps. The Holly is one of our most beautiful trees, as John Evelyn points out: "This _vulgar_ but _incomparable_ tree.... Is there under _Heaven_ a more glorious and refreshing object of the kind than an impregnable _hedge_ of near _three hundred_ feet in _length_, _nine_ foot _high_ and _five_ in _diameter_: which I can show in my poor _Gardens_ at any time in the year, glittering with its arm'd and vernished _leaves_? The taller _Standards_ at orderly distances blushing with their natural _Coral_."[89] This apparently was the identical hedge into which Peter the Great used to trundle his wheelbarrows. The barrows contained his courtiers. There was a nice run from the top of rising ground close at hand. It was at Sales Court, Deptford. [89] Evelyn, _Silva_. The spiny leaves of the Holly are unfortunately not nearly strong enough to save it from its enemies. The bark is apparently of a particularly delicious and toothsome nature, for sheep, cattle, and the ubiquitous rabbit are always delighted to destroy the trees. It has been noticed that wild hollies have at the base very spiny leaves, but that higher up on the tree (above the reach of cattle) the leaves have no spines at all. Sir Herbert Maxwell, in his _Memories of the Months_,[90] takes up this question. It is best to give the description in his own words:-- [90] Third Series, p. 60.