Novel features of the plastids in some deep-shade, antipodean thalloid liverworts

The chloroplasts in the inner thallus cells of Monoclea forsteri and Verdoornia succulenta contain giant grana often with over 100 thylakoids, a feature shared with another deep-shade liverwort Dumortiera hirsuta and with numerous extreme-shade vascular plants. In contrast, thylakoid architecture in Neohodgsonia mirabilis and Marchantia foliacea with small grana comprising only 5-10 thylakoids, is typical of that in most liverworts and mosses. In both the last two taxa and particularly Marchantia, bands of filaments, 15 nm in diameter, are closely associated with the thylakoids. These are most likely skeletal elements maintaining the spacial disposition of the internal membrane system. In Neohodgsonia dilated outer grana thylakoids contain bundles of tubules 35 nm in diameter. These are most conspicuous in the plastids in the stalks of the carpocephala.