This work is entirely concerned with the fossil flora of the Rhynie chert bed in Scotland. It falls into three main parts, in which more than 2500 peel-sections were studied. In the first Part a good deal of information about the morphology of the stems and sporangia of Nothia sphylla is described. This plant was first thought to be "The probable fertile region of Asteroxylon mackiei" but was given the name Nothia sphylla by Lyon (1964) after his discovery of a more probable fertile region of Asterouylon mackei. In the conclusion it is suggested that Nothin sphylla should be classified in the family Zosterophyllaceae. Part II describes two new Horneophyton lignieri fructifications with a more branched columella than previously known. Stomata are also described in the sporangial wall of Horneophyton. In Part III the results obtained from the study of the vertical succession of plants in a new section (Trench No. 2A) are compared with those obtained previously (1917, 1921) by Kidston & Lang from their study of a vertical section in the original Trench No. 1.