In nonflowering plants the works usually followed are for ferns, Hooker and Baker's Synopsis filicum; for mosses, Muller's Synopsis muscorum frondosorum, Jaeger & Sauerbeck's Genera et species muscorum, and Engler & Prantl's Pflanzenfamilien; for algae, de Toni's Sylloge algarum; for hepaticae, Gottsche, Lindenberg and Nees ab Esenbeck's Synopsis hepaticarum, supplemented by Stephani's Species hepaticarum; for fungi, Saccardo's Sylloge fungorum, and for mycetozoa Lister's monograph of the group. For the members of large genera, e.g.
The lowest Hepaticae have an extremely simple vegetative structure, little more advanced than that found in some of the higher Green Algae and very much simpler than in the large Red and Brown Seaweeds.
The venae hepaticae magnae join the vena cava posterior and thereby form with it the vena cava inferior.
Hooker enumerated twenty-one species of flowering plants, and seven of ferns, lycopods, and Characeae; at least seventyfour species of mosses, twenty-five of Hepaticae, and sixty-one of lichens are known, and there are probably many more.
In the absence, however, both of reproductive organs and of anatomical structure, it cannot be said that there is at present conclusive evidence for the existence of either Hepaticae or Musci in Palaeozoic times.
These fossil Hepaticae are unfortunately founded only on sterile fragments, and placed in the Liverworts on the strength of their resemblance to the thallus of Marchantia and other recent genera.