DOE 



[ 339 ] 



DOU 



and pteris, a fern ; spear-leaved Fern 

 [Polypodiaceae]. Linn., 2-Crypfoga- 

 mia l-Filices. Allied to Pteris.) 



Stove herbaceous ferns, with yellowish brown 

 spores. Division, chiefly in spring ; peat and 

 loam. Summer temp., 60 to 80; winter, 45 

 to 55. 



D, colli' net (hill). August. Brazil. 

 - cordifo'lia (heart-leaved). 



hasta'ta (halbert-leaved) , June. West In- 



dies. 1823. 



palma'ta (hand-shaped). . July. Carac- 



cas. 1821. 



sngittifo'lia (arrow-head leaved). . July. 



Walli'chii (Wallich's). East Indies. 



DOUBLE FLOWERS. Hybridizing, 

 aided by cultivation, gives birth to 

 these objects of the gardener's care. 

 To the uninitiated it seems incredible 

 that the double moss rose should be a 

 legitimate descendant from the briar ; 

 neither do the flowers of the Fair A: aid 

 of France appear less impossible deri- 

 vatives from those of the Ranunculus 

 platanifoliits ; nor bachelors' buttons 

 from the common butter-cup ; yet so 

 they are. Double flowers, as they are 

 popularly called, are more correctly 

 discriminated as the full flower, the 

 multiplicate flower, and the proliferous 

 flower. 



The full flower is a flower with its 

 petals augmented in number by the 

 total transformation into them of its 

 stamens and its pistils. One-petalled 

 flowers rarely undergo this metamor- 

 phosis, but it is very common in those 

 having many petals, as in the carna- 

 tion, ranunculus, rose, and poppy. But 

 this is not the only mode in which a 

 flower becomes full, for in the colum- 

 bine (Aqmlegia) it is effected in three 

 different ways, viz., by the multiplica- 

 tion of petals to the exclusion of the 

 nectaries ; by the multiplication of the 

 nectaries to the exclusion of the petals ; 

 and by the multiplication of the nec- 

 taries whilst the usual petals remain. 

 Eadiated flowers, such as the sunflower, 

 dahlia, anthemis, and others, become 

 full by the multiplication of the florets 

 of their rays to the exclusion of the 

 florets of their disk. On the contrary, 

 various species of the daisy, matricaria, 

 etc., become full by the multiplication 

 of the florets of the disk. 



The multiplicate flower has its petals 

 increased by the conversion of a portion 



of its stamens, or of its calyx. It 

 occurs most frequently in polypetalous 

 flowers. Linnoaus gives the only 

 instances we know of the conver- 

 sion of the calyx into petals, and 

 these are to be observed in the pink 

 (Dianthus caryophyllus), and a few of 

 the Alpine grasses. 



A proliferous flower has another 

 flower or a shoot produced from it, as 

 in the variety of the daisy popularly 

 known as the Hen-and-chickeiis. It 

 occurs also more rarely in the ranun- 

 culus, pink, marigold, and hawkweed. 

 A leafy shoot often appears in the 

 bosom of the double-blossomed cherry, 

 anemone, and rose. 



A due supply of moisture, but rather 

 less than the plant most delights in, 

 when the production of seed is the 

 desired object, a superabundant supply 

 of decomposing organic matter to its 

 roots, and an exposure to the greatest 

 possible degree of sun-light, are the 

 means successfully employed to pro- 

 mote excessive development of the 

 petals which characterize double flowers. 



By these means a greater quantity 

 of sap is supplied to the flower than 

 the natural extent of the petals can 

 elaborate ; and those parts required 

 for the extra elaboration are developed 

 at the expense of those not demanded 

 for the purpose. 



In double flowers, as was observed 

 by the late Sir J. E. Smith, the corolla 

 is much more durable than in single 

 ones of the same species, as anemones 

 and poppies, because, as he conceived, 

 in such double flowers the natural 

 function not being performed, the vital 

 principle of their corolla is not so soon 

 exhausted. Advantage 'may be taken 

 of this to prolong the duration of 

 flowers by cutting away the pistils or 

 stamens, whichever are least conspi- 

 cuous, with a sharp pair of pointed 

 scissors. 



DOUCIN STOCK. See Stock. 



DOUGLA'SIA. (In memory of the 

 unfortunate D. Douglas, botanical tra- 

 veller in North West America. Nat. 

 ord., Primeworts [Primulacese]. Linn., 

 b-Pentandria \-Monoyyniu. Allied to 

 ! Androsace.) 

 I An extremely rare hardy evergreen Alpine 



