94 



JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



contact takes place, but are not adhesive till such is the case. Hence 

 the former reveals the evolutionary history of the tendrils in the latter 

 species, in which the effects of a mere irritation are hereditary. 



The Passion-flower has only the peduncle transformed into a tendril, 

 which behaves precisely like that of our common Bryony ; but in this 

 latter plant the tendril appears to be more comparable to a stipule, having, 

 however, a somewhat anomalous origin. 



Another form of a climbing organ constructed out of a flowering 

 branch is that of a hook. This is seen in Uncaria, Artabotrys, &c, which 

 enables the plants to scramble if not to climb. 



A very different but useful metamorphosis of a peduncle is seen in 

 the structure of certain inflorescences. Thus, in the Fig the peduncle 

 forms the bag-like edible structure, the inner surface of which is densely 

 covered with flowers. The forerunner of this is seen in the open dish- 

 like form of Dorstenia, of the same family. It is comparable to the so- 

 called "general receptacle" of the Composite, well seen in the large plate- 

 like structure which carries all the florets and fruits of a Sunflower. The 

 same is edible in the Globe Artichoke. 



In whole groups of flowers the pedicel forms what is called the " recep- 

 tacular tube," such as the hep of the Rose and the cup round the pistil in 

 a Cherry blossom. In both, the sepals, petals, and stamens arise from the 

 rim, having been elevated by the growth of the tube. The tube or cup 

 may be adherent to the ovary. Such is the case in the Apple, in which 

 the two adjacent skins or epidermidos are not developed, so that the two 

 middle tissues become confluent ; the core really representing the inner 

 epidermis of the carpel only. 



The use of the receptacular tube, and explanation of its origin, appears 

 to have been as an organ for secreting honey. Such is well seen in the 

 Raspberry, in which it forms a circular honey-trough round the pistil. 



In the remarkable inflorescence of Marcgravia, the circlet of pitcher- 

 like structures are abortive flowers, instead of which the peduncle has 

 developed honey-pitchers. In several plants a not uncommon metamor- 

 phosis is for the pedicels to change into short thickened axes, and the 

 parts of the flowers to be replaced by bulb-scales, so that veritable and 

 propagative bulbils take the place of flowers, and in course of time fall to 

 the ground. This is a peculiar habit in some Onions. In Alpine grasses 

 little leafy buds often occur instead of flowers, and the panicle being 

 heavily weighted falls to the ground, where each of the tufts may then 

 strike root, and so form a new and independent plant. 



Useless Changes. — The peduncle or pedicels which terminate in 

 flowers are sometimes " proliferous," in which case the axis does not cease 

 to grow, but continues through the flower (instead of the pistil), and may 

 either become a perfect leafy shoot, or attempt to form a flower, the 

 parts being more or less foliaceous ; then it may proceed further and 

 finally terminate in a perfect flower. 



Cultivated Roses and the wild Water Avens (Geum rivale) are 

 peculiarly liable to this procedure. 



In the Feather Hyacinth (Muscari comosum syn. BeUevallia comosa) all 

 the flowers are aborted. The upper ones of the raceme are normally so 

 when wild — it is a common field weed in Malta — but under cultivation the 



