PROTECTION AGAINST UNBIDDEN GUESTS. , 241 



In the flowers of Vinca herbacea, indigenous to the Steppes of the Black Sea 

 (c/. figs. 263 ^' *• ''■"), the apices of both stamens and stigma are provided with tufts 

 of hairs which interlock and close the mouth of the corolla-tube, as it were, with 

 a plug of cotton-wool. One of the most curious of these arrangements is found 

 in the Eed Valerian (Centranthus ruber, fig. 263 ^). The corolla-tube is some 12 

 millimetres long and scarcely 1 millimetre in diameter; it is divided longitudinally 

 by a membraneous diaphragm into two tubes, of which the upper contains the long 

 style, whilst the lower one, produced into a spur, contains the honey. This lower 

 tube is lined throughout its entire length with hairs, which, although they present 

 no obstacle to the introduction of a proboscis, prevent little insects from creeping 

 in and stealing the honey. As may be seen in fig. 263 ^, these hairs project a con- 

 siderable distance into the interior of the tube. 



Hedges or palisades of erect elastic hairs or fringes, inserted on circular cushions 

 in tubular corollas, are not infrequently met with. These fringes stand straight 

 out into the tube and conceal its cavity. They are sometimes quite at the mouth 

 of the tube, as in Veronica officinalis, sometimes a little distance down the throat, 

 as in the Vervain ( Verbena officinalis), or quite at the base, as in Acanthus, Phlox, 

 Morminum, and Prunella. Fringed scales in rings are found in the flowers of many 

 Genetians and Passion-flowers. In several Rutaeese, Haplophyllum, for instance, 

 hairs from the bases of the stamens form a sort of lattice-work at the base of the 

 flower, whilst, in a species of Monotropa, the cushion beneath the stigma bears 

 radiating hairs which, reaching as far as the corolla, make an elegant grating. 

 The honey in Swertia perennis is secreted in little cup-like depressions near the 

 bases of the petals. The margins of the cups are fringed with hairs which converge, 

 and are so interwoven that the cups are protected by little cages. These few 

 examples are typical of a vast series of lattices, gratings, and the like, occurring in 

 flowers to shield the honey. 



Protection from undesirable visitors is also obtained in a great variety of ways 

 by the bending, twisting, or convergence of various parts of the flower, so that 

 the honey is hidden in grooves and special cavities. Amongst these are included 

 flowers with long, narrow tubes, into which the delicate proboscis of a butterfly 

 can be introduced, but which are too narrow for small insects to crawl into; also, 

 such as have various projections, cushions, and lobes of the corolla which narrow 

 or subdivide the aperture; finally, closed flowers which can only be opened by 

 powerful insects, and such as have their stamens so crowded that little insects 

 cannot obtain access to the honey. Several of these have been already described 

 and figured (p. 180, 181). 



We may also regard the periodic display of attractions to insects as being, in a 

 way, of the nature of a protection against unbidden guests. The subject has been 

 already alluded to (p. 156) in detail, so we need only add that the arrangements 

 obtaining in many moth-visited Caryophyllacese are also found in ZaluziansJcia 

 lychnidea, a Scrophularineous plant from the Cape. Its fiowers have a long honey- 

 secreting tube and spreading limb (as in Silene), the ten lobes of which are dark 



Vol. II. 66 



