OBSERVATIONS ON SOME OF THE PLANTS EXHIBITED. 
455 
the other species has regular flowers, it will probably disappear 
in the cross produce. 
Polypodium, sp .—A great variety of Ferns were exhibited 
by Mr. Ware, and the peculiarity in the genus referred to is the 
similarity of several species to the fronds of other genera. Thus 
one resembles a hart’s-tongue, another an Asplenium, a third 
has narrow grass-like leaves ; the interpretation being that, 
probably growing under similar conditions, they have developed 
similar fronds, though they retain the characteristic features of 
the reproductive elements which mark the genus. Mr. Henslow 
also called attention to another adaptation in that some had 
creeping aerial stems adherent to the surface of the flower-pots 
precisely like aerial Orchid-roots. 
Hybrid Polypodium.—A supposed cross between our 
English species and a foreign one was shown ; but, as the 
lecturer explained, in consequence of the impossibility of strictly 
crossing them artificially, it could not be proved that the result was 
a true hybrid. It had not much of P. vulgare in its appearance. 
Cyphomandra betacea.— This plant was introduced from 
South Brazil in 1836, and is miscalled the Tree Tomato. The 
oval orange-coloured egg-shaped fruits are edible. Mr. Henslow 
alluded to a popular conception that all purple fruits of the 
Solaneae are poisonous, but that all yellow, scarlet, or orange 
fruits are edible. Though a good rule for public use, it is not 
absolutely true, as the purple berries of Solanum nigrum and the 
Aubergine, the fruit of Solanum Melongena of the market, are 
exceptions. The purple-black berries of the Deadly Nightshade 
are, however, extremely dangerous. 
Pears with Oblique Ends. —Mr. Henslow explained the 
origin of the peculiar hump often present at the stalk end of 
Pears. It is due to the fact of the stalk extending obliquely from 
the tree, the Pear itself hangs vertically, so that the tension of 
support and the weight are two forces acting at an angle at the 
base of the Pear. To meet the resultant of these forces and 
prevent rupture, the Pear puts on additional tissues, causing the 
hump to arise on the further side of the stalk. This is only one 
instance out of many adaptations to mechanical strains and 
tensions to which plants are often subjected ; but in every case 
the plant meets the strain by putting a woody, fibrous, or other 
tissue requisite for the occasion. 
