SPINÆ, in Botany, thorns, rigid prickles: a species of arma, growing on various parts of certain plants for their defence; spinae ramosorum arcent pecora. On the branches we find examples in the pyrus, prunus, citrus, hippophaes, gmelina, rhamnus, lycium, &c.; on the leaves, in the aloë, agave, yucca, ilex, hippomane, theophrasta, carlina, &c.; on the calyx, in the carduus cnicus, centaurea, moluccella, galcopsis, &c.; on the fruit, in the trapa, tribulus, murex, spinacia, agrimonia, datura, &c.