Critical Plants noticed on the Excursion. 413 
scarcely longer than the capsules, and inner segments shorter than 
the capsule. Similarly, 1 should prefer to regard f. gerardi as a 
variety of J. coinpressns, rather than a separate species. In 
Ascherson and Graebner’s FI. Nordostd. Flacld. 175 (1898-9), jf. 
bufonius and f. ranarins appear under the “ Gesammtart ” f. 
bufonius. 
Zostera marina L. Both the type and the narrow-leaved form 
were abundant near the bridge leading to Hayling. The latter 
form is sometimes placed as a variety, sometimes as a hybrid of Z. 
marina and Z. nana ; but all the narrow-leaved forms of Z. marina 
which I have seen in situ seem to be states related to habitat 
conditions. It may be that a hybrid also occurs which simulates 
the narrow-leaved form of Z. marina. Z. nana also occurred near 
Hayling Island : it seems to prefer less salty water than Z. marina. 
Spartina townsendii H. and J. Groves in Dot. Exch. Club Rep. 
for 1880, 37 (1881); in Journ. Dot. xxi, t. 225 (1882); Stapf in 
Card. Chron. ser. 3, xliii, 33 (1908). The ecology of the Sparti- 
netum townsendii of the Hampshire coasts is well deserving of an 
intensive study. Personally, I do not regard it as occupying the 
place of any Salicornietum (cf. of Drit. Veg. Types p. 338); but as 
occupying a more outward or seaward zone. The extremely flat 
ground, the exceptionally soft mud, and the comparative absence of 
a tidal scour are special features of this habitat. At high tide, the 
Spartinetum resembles a reed-swamp of an open type. All 
Salicornieta, often reclaimed on this coast, occur on the land¬ 
ward margin of the Spartinetum ; and a very extensive Zosterctum 
marince occurs on the sea-ward side of it. The Zosterctum, also, is a 
special feature of this coast, and, so far at least as its large extent 
is concerned, is a unique feature among English plant-associations, 
though the Zosteretum is well-represented on the shores of some of 
the maritime lochs of north-eastern Scotland. 
The points of general interest in the above notes are here 
summarised:— 
1. Whilst it may be true that there are numerous endemic forms 
of plants in the British Isles slightly different from forms on the 
mainland of Europe, this hypothesis has no claims to acceptance 
until the British plants in question have been very carefully com¬ 
pared with the nearest related forms of the European mainland. 
