This plant had a long, somewhat slender, ridged stem, the ridges corresponding to the decurrent bases of the spirally arranged leaves (fig.
The ibex are connected with the wild goat by means of Capra nubiana, in which the front edge of the horns is thinner than in either the European C. ibex or the Asiatic C. sibirica; while the Spanish C. pyrenaica shows how the ibex-type of horn may pass into the spirally twisted one distinctive of the markhor, C. falconeri.
Many of the small female flowers borne on shoots with foliage of the Cupressus type consist of spirally disposed and not verticillate scales, e.g.
The usually crowded leaf-cushions are spirally arranged, and present no obvious orthostichies, thus differing from those of Sigillaria.
In addition to tentacles, there may be marginal cirri (Laodice) with a solid endodermal axis, spirally coiled, very contractile, and bearing a terminal battery of nematocysts.
The simple leaves, which are of small size and do not possess a ligule, are arranged spirally around the branched stem in the majority of the species.
The mosque of Khaseki, supposed to have been an old Christian church, is chiefly distinguished for its prayer niche, which, instead of being a simple recess, is crowned by a Roman arch, with square pedestals, spirally fluted shafts and a rich capital of flowers, with a fine fan or shell-top in the Roman style.
There is, however, a considerable amount of resemblance between the lophophore of Phoronis australis, with its spirally twisted ends, and that of a typical Brachiopod; nor do the structural details of the adult Brachiopods forbid the view that they may be related to Phoronis.
Thus, the cones of firs and the stroboli of the hop are composed of a series of spirally arranged bracts covering fertile flowers; and the scales on the fruit of the pine-apple are of the same nature.
The type-genus Botryopteris, represented in the Permo-Carboniferous of France and in both the Lower and Upper Carboniferous of Great Britain, had a rhizome, with a very simple monostelic structure, bearing spirally arranged compound leaves, with lobed pinnules, probably of a somewhat fleshy texture.