i88i.] HARDY PLANTS IN AND OUT OF DOORS. 323 



Grapes upon it will not increase in size unless oxygen gas be from 

 time to time admitted. The same phenomenon occurs during the 

 ripening of the Grapes ; oxygen has to be absorbed during the con- 

 version of tartaric acid into sugar, but a larger volume of carbonic 

 acid has to be evolved, and this is coincident with the results of well- 

 established experiments, uniformly testifying that carbonic acid is 

 given out abundantly by ripening fruit." 



The forms of fruits we are presented with are innumerable, both in 

 shape, size, and many other characteristics. A very curious one is 

 that of the Pandanus odoratissimus (?), whose fruit, we are told, when 

 ripe, explodes with great violence, and sometimes inflames spon- 

 taneously when dispersing its seed. Of our native British plants we 

 have Balsamina noli-me-tangere and Cardamine impatiens, both of 

 which have elastic seed-vessels, which immediately discharge their 

 contents by sudden collapse or recoil of their valves, and the contact 

 of a fly is quite sufficient for this purpose. W. Roberts. 



{To he continued.) 



HARDY PLANTS TN AND OUT OF DOORS. 



We are in the habit of comparing, rather unfavourably, our hardy 

 plants with our indoor exotics, looking upon the former as coarser than 

 the latter, and less attractive generally ; but the comparison is not a 

 fair one. No doubt a plant grown out of doors, exposed to all weathers, 

 looks a little less delicate than one grown under glass and by the aid 

 of artificial heat, just as fruit under glass takes on a more delicate 

 bloom and finish ; and in comparing the flowers of the border with 

 those of the hothouse, this should be remembered. It should also be 

 borne in mind that many of our hardy plants, in fact the most of them, 

 are also exotics, existing under, to them, unfavourable circumstances 

 in this country, although succeeding well enough for ordinary decora- 

 tive purposes. Take the common Geranium, for example. In the mass 

 out of doors it does show well enough j but do the individual flowers 

 equal those grown under glass in size and lustre ? No : and it is the 

 same with all hardy plants, or nearly all ; and there are many that are 

 never seen in perfection except when forced, of which the common 

 Spiraea japonica and the Dielytra spectabilis are good examples. Neither 

 are like the same plants when forced, or even just protected from the 

 weather. The plant is larger, the leaves of a more delicate hue and 

 more perfect, and the flowers altogether superior. Before the Spiraea 

 began to be forced, no one had any idea what a grand thing it was, and 

 it required to be seen well grown and flowered before gardeners would 

 believe in it. We remember it being tried for the first time many 

 years ago in a garden in Scotland, on the recommendation of a party 



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