576. For a full account of these, whether of former or actual use, see "Structural Botany" of the "Botanical Text Book," pp. 367, 392, as also for the principles which govern the accentuation of names. It is needful here to explain only those used in the Manuals and Floras of this country, for which the present volume is an introduction and companion. They are not numerous. 577. In arranging the species, at least those of a large genus, the divisions are denoted and graduated as follows: The sign § is prefixed to sections of the highest rank: these sections when they have names affixed to them (as Prunus § Cerasus) may be called subgenera. When the divisions of a genus are not of such importance, or when divisions are made under the subgenus itself, the most comprehensive ones are marked by asterisks, * for the first, * * for the second, and so on. Subdivisions are marked with a prefixed +; those under this head with ++; and those under this with =, if there be so many grades. A similar notation is followed in the synopsis of the genera of an order. 578. The interrogation point is used in botany to indicate doubt. Thus _Clematis crispa_, L.? expresses a doubt whether the plant in question is really the _Clematis crispa_ of Linnæus. _Clematis? polypetala_ expresses a doubt whether the plant so named is really a Clematis. On the other hand the exclamation point (!) is used to denote certainty whenever there is special need to affirm this. 579. For size or height, the common signs of degrees, minutes, and seconds, have been used, thus, 1°, 2', 3", stand respectively for a foot, two inches, and three lines or twelfths of an inch. A better way, when such brevity is needed, is to write 1^{ft}. 2^{in}. 3^{l}. 580. Signs for duration used by Linnæus were ☉ for an annual, ♂ for a biennial, ♃ for a perennial herb, [Symbol like numeral 5 without the top bar] for a shrub or tree. DeCandolle brought in ☉ for a plant that died after once flowering, ① if annual, ② if biennial. 581. To indicate sexes, ♂ means staminate or male plant or blossom; ♀, pistillate or female; [Symbol like ☿, but with two inverted breve accents over it], perfect or hermaphrodite. 582. To save room it is not uncommon to use ∞ in place of "many;" thus, "Stamens ∞," for stamens indefinitely numerous: "∞ flora" for pluriflora or many-flowered. Still more common is the form "Stamens 5-20," or "Calyx 4-5-parted," for stamens from five to twenty, calyx four-parted or five-parted, and the like. Such abbreviations hardly need explanation. 583. The same may be said of such abbreviations as _Cal._ for calyx, _Cor._ for corolla, _Pet._ for petals, _St._ for stamens, _Pist._ for pistil, _Hab._ for habitat, meaning place of growth, _Herb._ for herbarium, _Hort._ for garden. Also _l. c._, loco citato, which avoids repetition of volume and page.