FLOWER-GROUPS 65 
As I have pointed out in my ‘Grundriss der Blitenbiologie’ (p. 9, note), 
Herm. Miiller’s nine classes of flowers may readily be extended to twelve, inas- 
much as social flowers with exposed nectar may be distinguished from those 
with partially concealed nectar. For these two groups the symbols A’ and AB’ 
would be appropriate. The compound umbels of the Umbelliferae (especially 
of those with radiating marginal flowers), and the cymes (especially again those 
with neuter enlarged marginal flowers, e.g. those of Viburnum Opulus) also form 
an oecological unity, comparable with, e.g., the capitula of the Compositae, for 
like these they serve as a whole to entice insects, and also secure simultaneous 
pollination of numerous flowers by the passage of insects over the one continuous 
surface formed by the inflorescence. As examples of the class AB’, the corymbs of 
some Cruciferae may be taken, especially those of Iberis and Teesdalia, because in 
these the flowers at the margin of the inflorescence are larger than those in the 
middle. Accordingly, the following classes of flowers would result :—W (i.e. wind- 
pollinated or anemophilous flowers), Po, A, A’, AB, AB’, B, B’, H, F, D, KI. 
C. Verhoeff, in his work ‘Blumen und Insekten auf der Insel Norderney’ 
(Nova Acta Leop., Halle, lxi, 1894, pp. 174 and 175), attempts to change the 
classification of Herm. Miiller in accordance with the comparatively few plants in- 
vestigated by him with regard to their flower pollination on the island of Norderney'. 
He aang — 
. Wind-pollinated Flowers (W): no adaptation to insects, but occasionally 
dia by them. | Hippophaé rhamnoides. 
2. Actinomorphous Pollen-flowers (Po A): pollen adhesive, corolla sel coloured, 
no nectar. Cochlearia anglica, Helianthemum, Rosa, Polygonum aviculare. 
3. Zygomorphous Pollen-flowers (PoB): oho character as before. Sarothamnus 
scoparius. 
4. WVectar Flowers (Ne): no coloured perianth-leaves or petals, producing nectar, 
sticky pollen. Salix. 
5. Llowers with exposed nectar, but not social (A): brightly coloured perianth 
leaves or petals, nectar exposed, pollen sticky. Actinomorphous. Ranunculus 
Flammula, Batrachium, Honckenya, Parnassia. 
6. Flowers adapted in the same way but associated tn crowded small-flowered 
societies (AG). Most of the Rubiaceae and Umbelliferae. 
dy 7. Flowers with partly concealed nectar; quite or almost actinomorphous (AB): 
Ranunculus acris, repens, sceleratus ; Cardamine, Stenophragma, Brassica, Capsella, 
Sisymbrium, Cerastium, Rubus, Sedum, Glaux, Polygonum Persicaria. 
8. Flowers with completely concealed nectar; sometimes actinomorphous, some- 
times zygomorphous (B): pollen not concealed. Silene, Lychnis, Erodium, Epilobium, 
Vaccinium, Calluna, Pyrola (a specially adapted form, according to Verhoeff), 
Myosotis, Veronica, Euphrasia, Mentha, Stachys, Armeria, Orchis, Asparagus. 
9. Flowers with nectar equally well concealed, but the flowers united into capitulate 
societies (BG): pollen not concealed. Most Compositae, and Jasione—the latter 
with nectar not quite so deeply hidden. ’ 
1 See note on preceding page. 
DAVIS F 
