Fig. 289. One of the five stamen-clusters of the flower of American Linden, with accompanying scale. The five clusters are shown in section in the diagram of this flower, Fig. [277].
Fig. 290. Five syngenesious stamens of a Coreopsis. 291. Same, with tube laid open and displayed.
285. For which terms, see the Glossary. They are all Greek numerals prefixed to -andria (from the Greek), which Linnæus used for andrœcium, and are made into an English adjective, -androus. Two other terms, of same origin, designate particular cases of number (four or six) in connection with unequal length. Namely, the stamens are
Didynamous, when, being only four, they form two pairs, one pair longer than the other, as in the Trumpet Creeper, in Gerardia (Fig. [263]), etc.
Tetradynamous, when, being only six, four of them surpass the other two, as in the Mustard-flower and all the Cruciferous family, Fig. [235].
[286.] The Filament is a kind of stalk to the anther, commonly slender or thread-like: it is to the anther nearly what the petiole is to the blade of a leaf. Therefore it is not an essential part. As a leaf may be without a stalk, so the anther may be Sessile, or without a filament.