Ultrastructure of the protonematal propagules of Dicranoweisia cirrata (Hedw.) Lindb. The ultrastructural study points on the occurence of two successive states by the genesis of the protonematal propagules in this species: a formation state followed by a maturation state which is characterized by a particular lipophilic substance accumulation. Furthermore, it is confirmed that these propagules belong to the protonematal phase of the gametophyte.

  The distribution of the 15 Drepanocladus taxa, presented in detail in this paper, can be grouped in 5 distinct patterns related to longitudinal and latitudinal extent, lowland versus alpine presence, and the maximal limit of Pleistocene glaciation.

- Drepanocladus aduncus and D. uncinatus: widely distributed, common in arctic-alpine areas, as well as south of the glacial limit. Fossil localities are included in the present range but are restricted to former refugial and periglacial areas (this is most likely because suitable fossiliferous deposits are restricted to these areas).

- Drepanocladus exannulatus and D. revolvens: widely distributed, common in arctic-alpine areas, but not extending south of the glacial limit. Fossil localities are in former refugial areas and along the southern margin of the present range.

- Drepanocladus aduncus var. kneiffii, D. capillifolius, D. fluitans, D. pseudostramineus and D. vernicosus: widely distributed, rare in arctic-alpine areas, restricted to former glaciated terrain or periglacial areas. Fossil localities are in former refugial areas and along the southern margin of the present range.

- Drepanocladus badius, D. lapponicus, D. lycopodioides var. brevifolius, and D. tundrae: arctic or arctic-alpine. Fossil localities are in refugial areas and former periglacial areas in Alaska, now far disjunct from present range.

- Drepanocladus crassicostatus and D. sendtneri: western arctic-alpine. Fossil localities are in former refugial areas and (in the case of D. sendtneri) in periglacial areas south of the ice-sheet in mid-western North America.

  The dendroid moss Hypopterygium commutatum C. Müll. (Hypopterygiaceae) from New Zealand possesses duct systems running longitudinally through the stem. Development and patterns of distribution of these ducts have been investigated using light and electron microscopy.

  Each duct initiates near the stem apex or under dormant buds that even may grow out into a twig. The lateral apical cells act as duct initials; descendents undergo divisions into future epithelial cells with dense cytoplasm. The corners of the cells expand presumable shizogenously into intercellular space. The sheathing cells are mostly uniseriate. Electron microscopic observations show that the ducts are often filled with a homogenous or sometimes granular content of unknown composition. The ducts end in the parenchyma.

  The length of the ducts varies from 1 to 5.7 mm already measured. They are neither branched nor do anastomose and are not associated with other structures. The function of the ducts is yet unknown. We do not know whether they act as secretory organs or as structures that may support water transport or water reserve in the highly developed gametophyte.

  Stephensoniella brevipedunculata Kash. - a monotypic taxon, endemic to India, now belongs to the category of ‘threatened’ liverwort as it is fast disappearing from its well-known restricted sites of occurrence. This is primarily due to a curious reproductive limitation in which the spores apparently fail to respond in vivo though fully viable in vitro. The reliance on reproduction by tubers in nature imposes serious limitations on its dispersal. Morphotaxonomic details have been provided for this rare taxon laying stress on several interesitng facets not elucidated clearly so far. The structure of the oil body and SEM details of spores have been presented for the first time with the latter revealing unique sporoderm characteristics. It has been stressed that suitable steps be taken to conserve this prestigious Indian liverwort.