98 INTRODUCTION 
all serving to attract animals that effect pollination, so that they are described as 
nuptial, other nectaries are sometimes to be found on the vegetative organs of plants, 
which serve totally different purposes, and have at most but an indirect relation to the 
crossing of flowers. These organs, which are described by Delpino as extra-nupztial, 
by Kny as asexual nectaries, serve to allure ants, which afford protection to the plants 
against the attacks of other animals, and so form a kind of body-guard, Sprengel 
(‘Entd. Geh.,’ p. 356) noticed these extra-floral nectaries, and also the visits of ants 
Nae ee 
qs A> Gy a = Si Ape 
Fic. 15. Various forms of Nectar-guides in Evodium Cicutarium. (From Nature.) (1) The two 
upper petals are relatively shorter, broader, and coloured a darker red, with two or three dark veins; the 
two lower lateral ones are relatively longer, narrower, and coloured brighter red, with a dark mid-rib; the 
fifth petal (the middle of the three lower) is the longest, narrowest, brightest, and is veinless. (2) The two 
upper petals have each three long veins; on each of the two lateral lower petals there are one or two 
somewhat branched lines; the fifth (middle lower) has a central vein. (3) The two upper petals have three 
veins that are in part branched and possess a dark basal spot; the three lower have each three veins. 
(4) Three petals have three partially-branched veins and a dark basal spot (largest in the middle one) ; 
two petals have each only three veins. (5) The two upper petals have each three branched veins and 
a large dark basal spot ; of the three lower petals the two lateral ones have each three veins and a smaller 
dark spot; the middle one has three veins. (6) The two upper petals have a spot that covers almost the 
entire surface, as well as the three veins; the two lateral of the lower petals have three veins, and 
a medium-sized spot, the middle lower petal has also three veins and a somewhat smaller spot. (Cf. 
Knuth, ‘Blumen und Insekten auf den nordfriesischen Inseln,’ p. 52.) 
to Vicia sepium: ‘This plant provides nectar for insects not only in its flowers but 
also on its stipules. These have on their under side a small cavity, which is not 
of so dark a green as the leaves, but is slightly yellowish and contains a drop of 
nectar. The great wood-ants search eagerly for this fluid.’ The significance of 
the extra-floral nectaries as secretory organs serving to attract protective ants was 
first recognized by Delpino (1873): but his investigations are outside the actual limits 
of flower pollination, and so are only referred to here. 
According to what has been just stated, nectaries may be classified as— 
i. Nuptial: 
1. Intra-floral. 
2. Circum-floral. 
3. Extra-floral. 
ii. Extra-Nuptial. 
Even in pollen flowers a marking like a nectar-guide is sometimes found on 
the petals, and this has been described as a pollen-guide. This term does not seem 
to me to be correct, for the mark always points to the place where nectar should 
occur, not to where pollen is found. I would therefore propose the term pseudo- 
nectar-guide. The erect yellow standard of the pollen flower Ononis natrix, for 
example, possesses red streaks running towards the base of the flower. 
Sap. As Sprengel (‘ Entd. Geh.,’ p. 3) long ago pointed out, Orchis latifolia 
and O. Morio have the typical structure of nectar flowers, but contain noJnectar. 
