Floristik, Geographie, Systematik etc. 
255 
sable, le Flora lusitanica de Brotero etant dejä tres rare et in- 
complet. L’etude de flores partielles facilitera sans doute la publication 
d’une flore generale du pays. Pour cette raison j’ai commence le 
catalogue ou plutöt une flore resumee du bassin du Monolego, 
tres riche et interessante. Dans cette premiere partie je men- 
tionne les Cryptogames vasculaires (31), les Gymnospermes (5) 
et les Monocotyledones. (Pandanales 5; Helobiae 24; Glumiflorae 
(Graminae 60, Cyperaceen 57); Spathiflorae 7; Liliiflorae 53; Micro- 
spermae 32). J. Henriques. 
Hervier, J., Excursions botaniques de M. Elisee Rever- 
chon dans le massif de la Sagra (Espagne) 1904 —1905. 
(Bull. Acad. int. Geogr. bot. 1906. XV. p. 201-232 et 1907. XVI. 
p. 33—64, 193—208 et 230—231. 1906.) 
E. Reverchon a poursuivi ses explorations dans le massif de 
la Sagra en visitant en 1904 et 1905 le Barrancon Valentina, 
les Sierras de la Malessa et de la Cabrilla. Comme dans les me- 
moires precedents analyses ici (T. XCVIII, p. 471 et T. XCiX, p. 
412), l’auteur enumere les especes les plus interessantes trouvees 
dans cette region, discute les formes critiques et decrit plusieurs 
especes et Varietes nouveiles: Ranuncalus malessanus Deg. et Herv. 
sp. n., Ptilotrichum (. Alyssum ) Reverchonii Deg. et Herv. sp. n., Si- 
symbrium pseudo-Boissieri Degen sp. n., sans diagnose, Saurothamnus 
Reverchonii Deg. et Herv. subsp. n. croissant sur le calcaire, Atha- 
manta hispanica Deg. sp. n., Centaurea gienensis Deg. et Debeaux 
sp. n., C. Hervieri Deg. sp. n., Campanula malacitana Deg. et Herv. 
sp. n. prise jusqu’ici pour le C. mollis L., Verbascum Hervieri Deg. 
sp. n., Nepeia gienensis Deg. et Herv. sp. n. confondu avec N. reti- 
culata Dess., Scilla Reverchonii Deg. et Herv. sp. n. — Galium tubercu- 
latum Presl. et SideritisEndressi Willk. sont nouveaux pour l’Espagne. 
Les Hieracium ont ete revus par Arvet-Touvet, les Graminees 
par Hackel. J. Offner. 
Moss, C. E., Succession of Plant Formations in Britain. 
(Report British Association, York (1906) p, 742—743. 1907.) 
A plant formation is regarded as a historical series of plant 
associations, beginning as an open association, passing through inter- 
mediate associations, and finally becoming a closed association. An 
open association is usually dominated by one plant, and the number 
of other species is small. An intermediate association either consists 
of a number of smaller Vegetation units (plant societies), or is domi¬ 
nated by several plants, each of which possesses the same plant 
form. The number of species in an intermediate plant association is 
offen very large. A closed association is again dominated by one 
plant, and the number of plants is small. The ground is not fully 
occupied by plants in an open association, whereas in a closed 
association plants cover all the available ground. As examples of 
this concept of a plant formation, we select the following. The plant 
formation of sand dunes begins as an open association, a. of Strand 
plants (. Atriplex, Salsolaj etc.), or b. of Agropyrum, or c. of Psamma. 
It then passes through intermediate associations a. of Festuca rubra (y. 
arenaria ), and other grasses, or b. of dune marsh plants (. Hydroco- 
tyle, Scirpus maritimus, etc.); it ultimately becomes a closed associ¬ 
ation of heath plants {Ononis, or Salix repens or Calluna). Its later 
stages are frequently destroyed by human operations. In the same 
