High temperature alters the growth reaction of Pottia protonemata.

Under gravistimulation, dark-grown protonemata of Pottia intermedia revealed negative gravitropism with a growth rate of approximately 28 micrometers hour-1 at room temperature (20 degrees C). In 7 days, the protonema formed a bundle of vertically oriented filaments. At an elevated temperature (30 degrees C), bundles of vertically growing filaments were also formed.

Influence of gravity on the photomorphism of secondary moss protonemata.

In dark-grown plantlets of the moss, Pottia intermedia, negatively gravitropic secondary protonemata differentiate from the superficial cells of leafy shoots. When transferred to the light, distal parts of the protonemata nearest to the apical cells begin to ramify and the apical cells of the side branches as well as of the main protonemal filaments often differentiate as buds. Dark-grown protonemata were oriented horizontally and illuminated from below with white light of different intensities.

Gravitropism in caulonemata of the moss Pottia intermedia.

The gravitropism of caulonemata of Pottia intermedia is described and compared with that of other mosses. Spore germination produces primary protonemata including caulonemata which give rise to buds that form the leafy moss plant, the gametophore. Primary caulonemata are negatively gravitropic but their growth and the number of filaments are limited in the dark.

Influence of gravity on spatial orientation and morphogenesis of moss sporophytes.

During the growth and development of the sporophytic capsules of some moss species, negative gravitropism is changed for a positive one. Horizontal clinostat rotation induced unregulated growth of the sporophytes and their twisting; some of sporophytes remained straight, however. It has been established that the change of the gravitropic reaction is related to capsule formation and to the redistribution of amyloplast cells of the sporophyte graviperception zone.

Gravity effects on the [correction of thr] growth and development of moss secondary protonemata.

The superficial cells of dark-grown moss shoots give rise to negatively gravitropic protonemata, whatever the orientation of the shoot. Shoot orientation, however, does affect from which side of the shoot the protonemata form and the direction of their growth. Protonemata from horizontal shoots grow out at a near-right angle to their supporting axes and are initiated more or less evenly along the upper side of the stem.