Homologies of the flower and inflorescence in the early‐divergent grass Anomochloa (Poaceae)

Abstract

Using the median part of the innermost bract as a locator, we tentatively homologize the inner bract of the Anomochloa partial inflorescence with the palea of other grasses. In this interpretation, the pattern of monosymmetry due to stamen suppression differs from that of Ecdeiocolea.

Flower Structure

“…Dehiscence is latrorse in Streptochaeta (Arber 1929;Sajo et al 2009), whereas in Anomochloa it is introrse proximally and latrorse distally (Sajo et al 2012). In contrast, in grass species with three anthers, the abaxial anther is latrorse or introrse, whereas the lateral anthers are consistently extrorse (Anton and Astegiano 1973).…”

“…In contrast, Anomochloa has a single structure that presumably corresponds to a single stylar branch and stigma (Sajo et al 2012). All Pharoideae have one style with three branches and three stigmas, as does Puelia (Puelioideae), but Guaduella (also Puelioideae) has only two branches and two stigmas.…”

“…The filament in Streptochaeta and Anomochloa is centrifixed (¼ pseudobasifixed), such that the filament is completely surrounded by the connective at the point of insertion (Arber 1929;Judziewicz and Soderstrom 1989;Sajo et al 2009Sajo et al , 2012; such anther attachment is often associated with buzz pollination. In most other grasses, the filament is attached to the abaxial side of the anther and elongates swiftly at anthesis so that the anther is exserted from the flower.…”

“…Styles in most grasses are solid, a condition rarely found in monocots (Rudall et al 2005;Sajo et al 2012), although open styles are described in Pharus (Pharoideae) (Sajo et al 2007). Pollen tubes are then transmitted through the "stylar core" (Arber 1934).…”

I. Subfamily Anomochlooideae Pilg. ex Potztal (1957)

“…It is rare and nearly extinct in the wild and difficult to maintain in cultivation. It has been the subject of several careful developmental and anatomical studies, which describe in detail the nature of the floral parts and subtending bracts (Judziewicz et al 1999;Judziewicz and Soderstrom 1989;Sajo et al 2012 Leaves with auricles; ligule absent. Inflorescence spike-like, with spirally arranged, contracted lateral branches, each bearing 11 spirally arranged bracts with varying morphologies, the sixth bract ending in a long coiled awn.…”