Floral Organogenesis in Five Genera of the Marantaceae and in Canna (Cannaceae)

Abstract

The paired flowers of all species of the Marantaceae studied, except Monotagma plurispicatum, are produced through the division of an apical meristem with a tunica‐corpus structure. The solitary flowers of M. plurispicatum develop from a similar meristem which does not bifurcate. The paired flowers of Canna indica are produced in the axil of a florescence bract through the formation of a bract and an axillary flower on the side of the primordium which gives rise to the largest flower of the pair. The sequence of organ initiation for both families is: calyx, corolla and inner androecial whorl, outer androecial whorl, gynoecium. The sequence of sepal formation is opposite in the two families. In the Cannaceae it leads directly into the spiral created by the formation of the other organs, while in the Marantaceae the sequence of sepal formation follows a spiral opposite to that of the other floral organs. The members of the corolla and inner androecial whorl separate from common primordia. In general these common primordia separate into a petal and an inner androecial member through the initiation of two growth centers, at the same level, in the dorsal and ventral flanks of the primordium. In Ischnosiphon elegans and Pleiostachya pruinosa the stamen is initiated at a lower position than the petal in the ventral flank of the common primordium. A similar pattern of initiation is described for the callose staminode in Marantochloa purpurea and Canna indica. This pattern is interpreted as a variation on the more generalized pattern of inner androecial formation found in the other genera.

Floral vasculature and ontogeny in Canna indica

“…Th e observations presented here on fl oral vasculature and ontogeny in Canna indica indicate that the labellum and functional stamen incorporate elements of two androecial members each, rather than three, one or half, as suggested by previous studies of Cannaceae (Th ompson 1933, Pai 1963, Kirchoff 1983b, Almeida 2013.…”

“…Several morphologists have claimed that the stamen of Canna belongs to the inner androecial whorl (Eichler 1875, Rao and Donde 1955, Pai 1963, Kirchoff 1983b). Costerus (1916,1917) suggested that the anther and petaloid appendage are members of diff erent whorls.…”

“…Comparing the labellum in Canna with the hooded staminode (which encloses the style and stigma before pollination) of Marantaceae, Pai (1963) suggested that the former was of unitary constitution, but illustrated these descriptions with diagrams only. Kirchoff (1983b) reported work on fl oral organogenesis in C. indica and stated that the labellum is composed of an inner androecial member. Th e images of diff erent phases that were provided in that study are insuffi cient, and most are unrecognisable because of the printing technology used.…”

The Immense Diversity of Floral Monosymmetry and Asymmetry Across Angiosperms

“…Marantaceae and Cannaceae consistently have conspicuously asymmetric flowers with corolla, androecium and gynoecium involved, especially elaborate in Marantaceae (Kirchoff, 1983;Kress, 1990;Classen-Bockhoff & Heller, 2008). They may be seen as an elaboration of monosymmetric flowers as in the other six families of the order, of which a few Zingiberaceae also have asymmetric flowers (Hedychium) (Kress, 1990).…”

“…In vertebrates the organisational internal asymmetry is not conspicuous externally; however, some specialized groups also have an external non-enantiomorphic asymmetry, such as snail-eating snakes with asymmetric jaws (Hoso et al, 2007). If enantiomorphic flowers occur on one individual, they are often components of a system with pendulum symmetry (Goebel, 1908;Endress, 1999;Kirchoff, 2003;Hardy et al, 2004).…”