Island Life Part 22

74. Pisidium pusillum, _var._ GRANDIS.

75. ,, ,, ,, CIRCULARE. Wales.

76. ,, nitidum, _var._ GLOBOSUM.

{359} UNIONIDae.

77. Unio tumidus, _var._ RICHENSIS. Regent's Park. Peculiar form.

78. ,, pictorum, _var._ LATIOR. England.

79. ,, ,, ,, COMPRESSUS. England.

80. ,, margaritifer, _var._ OLIVACEUS.

81. Anodonta cygnaea, _var._ INCRa.s.sATA. England.

82. ,, ,, ,, PALLIDA. England, Ireland.

ESTUARINE OR MARINE PULMONOTRANCHS.

83. a.s.sIMINEA GRAYANA. Thames Estuary.

_Peculiarities of the British Flora._--Thinking it probable that there must also be some peculiar British plants, but not finding any enumeration of such in the _British Floras_ of Babington, Hooker, or Bentham, I applied to the greatest living authority on the distribution of British plants--the late Mr. H. C. Watson, who very kindly gave me the information I required, and I cannot do better than quote his words: "It may be stated pretty confidently that there is no 'species' (generally accepted among botanists as a good species) peculiar to the British Isles. True, during the past hundred years, nominally new species have been named and described on British specimens only, from time to time. But these have gradually come to be identified with species described elsewhere under other names--or they have been reduced in rank by succeeding botanists, and placed or replaced as varieties of more widely distributed species. In his _British Rubi_ Professor Babington includes as good species, some half-dozen which he has, apparently, not identified with any foreign species or variety. None of these are accepted as 'true species,' nor even as 'sub-species' in the _Students' Flora_, where the brambles are described by Baker, a botanist well acquainted with the plants of Britain. And as all these nominal species of Rubi are of late creation, they have truly never been subjected to real or critical tests as 'species.'"

In my first edition I was only able to name four species, sub-species, or varieties of flowering plants which were believed to be unknown on the continent. But much attention has of late years been paid to the critical examination of British plants in comparison with continental specimens, and I am now enabled to give a much more {360} extensive list of the species or forms which at present seem to be peculiar. For the following list I am primarily indebted to Mr. Arthur Bennett of Croydon. Sir Joseph Hooker has been so kind as to examine it carefully and to give me his conclusions on the relative value of the differences of the several forms, and Mr. Baker, of Kew, has also a.s.sisted with his extensive knowledge of British plants.

LIST OF SPECIES, SUB-SPECIES, AND VARIETIES OF FLOWERING PLANTS FOUND IN GREAT BRITAIN OR IRELAND, BUT NOT AT PRESENT KNOWN IN CONTINENTAL EUROPE. BY ARTHUR BENNETT, F.L.S. THE MOST DISTINCT AND BEST DETERMINED FORMS ARE MARKED WITH AN ASTERISK.

1. *Caltha radicans (Forst.). "A much disputed species, or form of _C.

pal.u.s.tris_. It is a relatively rare plant." (J. D. H.) "Certainly distinct from the Scandinavian form." (Ar. Bennett.)

2. *Arabis petraea (Lam.) _var._ grandifolia (Druce). Scotch mountains.

"The larger flowers alone distinguish this." (J. D. H.)

3. Arabis ciliata (R. Br.). In Nyman's _Conspectus Florae Europaeae_ this species is given as found in England and Ireland only. "A very much disputed form of a plant of very wide distribution in Europe and North America." (J. D. H.)

4. Bra.s.sica monensis (Huds.). "This and the continental _B.

cheiranthus_ (also found in Cornwall) are barely distinguishable from one another." (J. D. H.)

5. Diplotaxis muralis (D. C.) _var._ Babingtonii (Syme). South of England. "A biennial or perennial form; considered to be a denizen by Watson." (J. D. H.)

6. *Helianthemum guttatum (Mill), _var._ Breweri (Planch). Anglesea.

"Very doubtful local plant. _H. guttatum_ (true) has lately been found in the same locality." (J. D. H.)

7. *Polygala vulgaris (L.), _var._ grandiflora (Bab). Sligo, Ireland.

"A very distinct variety." (J. D. H.)

8. Viola lutea (Huds.), _var._ amoena (Symons). "_V. lutea_ itself is considered to be a form of _V. tricolor_, and _V. amoena_ the better coloured of the two forms of _V. lutea_." (J. D. H.)

9. *Cerastium arctic.u.m (Lange), _var._ Edmonstonii (Beeby). Shetland Is. "But _C. arctic.u.m_ is referable to the very variable _C. alpinum_."

(J. D. H.) "Near to the European _C. latifolium_." (Ar. Bennett.)

10. *Geranium sanguineum (L.), _var._ Lancastriense (With.).

Lancashire. "A prostrate local form growing out of its native soil in sand by the sea." (J. D. H.) Mr. Bennett writes: "I have grown _G.

sanguineum_ and its prostrate variety in sand, and neither became Lancastriense."

11. Genista tinctoria (L.), _var._ humifusa (d.i.c.kson). Cornwall. "A dec.u.mbent hairy form confined to the Lizard." (J. D. H.)

12. Cytisus scoparius (Link.), _var._ prostratus (Bailey). Cornwall. "A prostrate form." (J. D. H.)

13. Anthyllis vulneraria (L.), _var._ ovata (Bab.). Shetland Is. "A slight variety." (J. D. H.)

14. *Trifolium repens (L.), _var._ Townsendii (Bab.). Scilly Isles. "A {361} well-marked form by its rose-purple flowers. Confined to the Scilly Isles." (J. D. H.)

15. *Rosa involuta (Sm.), _var._ Wilsoni. (Borrer.) Wales. "There are a mult.i.tude of forms or varieties of _R. involuta_, and _R. wilsoni_ is one of the best-marked, found on the Menai Straits and Derry."

(J. D. H.)

16. Rosa involuta _var._ gracilis (Woods). "This is considered by many as one of the commonest forms of _R. involuta_." (J. D. H.)

17. Rosa involuta _var._ Nicholsoni (Crepin). "Another slight variety of _R. involuta_." (J. D. H.)

18. Rosa involuta _var._ Woodsiana (Groves). "A Wimbledon Common variety of _R. villosa_." (J. D. H.)

19. Rosa involuta _var._ Grovesii (Baker). "Mr. Baker thinks this of no account." (J. D. H.)

20. Rubus echinatus (Lind.). "A variety of the widely spread _R.

Radula_, itself a form of _R. fruticosus_." (J. D. H.)

21. *Rubus longithyrsiger (Lees). "Mr. Baker informs me that this is a very distinct plant never yet found on the continent." (J. D. H.)

22. Pyrus aria (Sm.) _var._ rupicola (Syme). "A very local form, confined to Gt. Britain, and owing its characters to its starved position." (Baker.)

23. Callitriche obtusangula (Le Gall), _var._ Lachii (Warren).

Cheshire. "This is intermediate between two sub-species of _C. verna_."

(J. D. H.)

24. *Oenanthe fluviatilis (Coleman). South of England. "The fluitant form of _ae. Ph.e.l.landrium_." (J. D. H.)

25. Anthemis arvensis (L.), _var._ anglica (Spreng). N. Coast of England. "A maritime form with more fleshy leaves formerly found near Durham. It has other very trifling characters." (J. D. H.)

26. Arctium intermedium (Bab.). "There are two sub-species of _A.

lappa_, _majus_ and _minus_, each with varieties, and this is one of the intermediates." (J. D. H.)

27. Hieracium holosericium (Backh.). Scotch Alps.

28. H. gracilentum (Backh.). ,,