An Embryological Study of Kava, Piper methysticum

Abstract

An embryological study of Piper methysticum Forster f. (Piperaceae), undertaken to identify the probable cause for the absence of fruits in cultivated varieties, has revealed that the majority of plants in all the cultivars examined bore only male flowers. The anthers are tetrasporangiate and the anther wall comprises a well-developed endothecium with fibrous thickenings, two middle layers and a glandular tapetum. Meiosis is normal and simultaneous cytokinesis leads to tetrahedral microspore tetrads. Pollen degeneration was observed but was of very rare occurrence. The pollen grains are released when they are 2-celled and appear to be healthy and capable of germination. The unilocular ovary contains a single basal ovule which is orthotropous, bitegmic, and crassinucellar. Both integuments contribute to the formation of the micropyle. The development of the female gametophyte conforms to the tetrasporic Fritillaria-type. No abnormalities were noticed either in meiosis of the megaspore mother cell or in subsequent development leading to the formation of the mature embryo sac. Occasional parthenocarpy was observed but without viable seeds being present inside. It is suggested that, although the lack of fruit formation in this species is not because of any deficiencies in its embryological development, it may be due to a simple self-incompatibility mechanism.

Embryology of Manekia naranjoana (Piperaceae) and the origin of tetrasporic, 16‐nucleate female gametophytes in Piperales

“…There are now at least five female gametophytic variants known within Piperaceae: the 16‐nucleate Drusa‐type with a diploid central cell in Manekia (this study) or diploid and higher in Zippelia (Lei et al, 2002), the 16‐nucleate Penaea‐type with a tetraploid central cell in Manekia (this study), the Fritillaria‐type in Piper with a seven‐celled/eight‐nucleate female gametophyte with a tetraploid central cell (Maheshwari and Gangulee, 1942; Swamy, 1945; Yoshida, 1960; Kanta, 1962; Nikiticheva et al, 1981; Prakash et al, 1994), and two different functional variants of the 16‐nucleate Peperomia‐type in Peperomia generally with either eight‐ or 14‐nucleate central cells (Swamy, 1944; Nikiticheva et al, 1981; Plyushch, 1982; Smirnov and Grakhantseva, 1988; older studies reviewed in Maheshwari, 1937).…”

“…All are tetrasporic, initiating female gametophyte ontogeny from four free megaspores (the haploid products of meiosis), which then undergo two mitoses to ultimately produce 16 haploid chromosome sets (partitioned into either eight or 16 nuclei during development). In Piper , the Fritillaria type has been reported (eight‐nucleate with pentaploid endosperm) (Maheshwari and Gangulee, 1942; Swamy, 1945; Yoshida, 1960; Kanta, 1962, Nikiticheva, 1981, Prakash et al, 1994); in Peperomia , the Peperomia type (16‐nucleate with 8‐15 ploid endosperm) (Campbell, 1901, 1902; Brown, 1908; Johnson, 1914; Swamy, 1944; Nikiticheva et al, 1981; Plyushch, 1982; Smirnov and Grakhantseva, 1988), and in Zippelia , the Drusa type (16‐nucleate with triploid or higher endosperm) (Lei et al, 2002). The status of Manekia and Verhuellia remain completely unknown.…”

Estrutura genética e sistema de acasalamento de Piper hispidinervum

“…Apenas três espécies de Piper foram estudadas quanto à auto-incompatibilidade, P. methysticum se mostrou auto-incompatível (Prakash et al, 1994) e P. nigrum e P. arieianum são autocompatíveis (Martin & Gregory, 1962;Marquis, 1988).…”

Gynoecium diversity and systematics of the paleoherbs

“…OLule 1 per gynoecium, small to medium (probably large in Zippelia), crassinucellar, bite<gmic, but unitegmic in Peperomia (see also Schmitz, 1872a,b;Johnson, 1902, 19 10.19 14;Fisher, 19 14;Hauser, 191 8;Abele, 1923;Fagerlind, 1939;Quibell, 194 1 ;hlaheshwari & Gangulee, 1942;Joshi, 1944;Martinoli, 1948;Maugini, 1950Maugini, , 1953Murty, 1959a,b;Yoshida, 1960;Kanta, 1963;Nikiticheva, 1981 a;Nikiticheva, Yakovlev & Plyusuch, 1981;Omori, 1982;Prakash & Kin, 1982;Tucker, 1982;Prakash, Brown & Wang, 1994), orthotropous, basal, erect. An aril is lacking.…”