OTHOXXA 



THE BULB BOOK 



OXALIS 



shallow cultivation is useless to a 

 plant that has such large tuberous 

 roots ; therefore trenching 3 ft. deep 

 will not be too much, if the best 

 results are desired. Perfect drainage 

 a most important item considering 

 our cold winter rains is also thus 

 assured. The simplest way to in- 

 crease the Ostrowskia is from seed. 

 These are ripened freely, and should 

 be sown in cold frames in autumn or 

 spring. The young plants when 

 about 6 ins. high are large enough to 

 place in the open air, but they will 

 not reach the flowering stage 

 for three or four seasons. 



OTHONNA (othone, linen ; 

 in reference to the soft 

 downy clothing of the leaves). 

 Nat. Ord. Compositse. 

 There are two or three 

 tuberous-rooted species in 

 this genus, the best-known 

 probably being 



O. tuberosa. A tuberous- 

 rooted Ragwort from S. 

 Africa, having broadly oval 

 stalked leaves, gradually becoming 

 smaller up the stems. The yellow 

 flower-heads appear about August at 

 the ends of the shoots. (JJot. Mag. 

 t. 4038.) 



This species requires the protection 

 of a greenhouse in winter, although it 

 may be grown in the open air during 

 the summer months. It may be 

 increased by division of the roots, or 

 by cuttings arising from them. 



OXALIS (oxys, acid ; referring to 

 the taste of the leaves), WOOD - 

 SORREL. Nat. Ord Geraniacese. A 

 genus containing over two hundred 

 species, mostly herbaceous plants, 

 many of which have fleshy, bulb-like, 

 or tuberous root-stocks, usually three- 

 lobed clover-like leaves (0. ennea- 

 j)hylla has nine to twenty leaflets), 



and regular tubular or bell-shaped 

 flowers, which are twisted in bud, 

 and only open well in the sunshine, 

 closing in the evening. Stamens ten, 

 five short and five long. Stigmas 

 usually papillose. 



The genus Oxalis is remarkable, 

 and interesting botanically for having 

 styles and stamens of three different 

 lengths what have been termed 

 long-styled, short-styled, and mid- 

 styled forms existing. Darwin called 

 attention to this feature in his 

 volume on The Different Forms of 



Fio. 287. Oxalis flowers with petals removed, showing long- 

 styled, mid-styled, and short-styled forms. The dotted 

 lines with arrows show the stamens that should supply 

 pollen to the stigmas (S) to ensure legitimate fertilisation. 



Flwuers on Plants of the Same Species, 

 from which the accompanying figure 

 (Fig. 287) is taken. The dotted lines 

 with arrows show from which stamens 

 the pollen should be taken to properly 

 fertilise the stigmas (S) of other 

 flowers. Styles and stamens of 

 different lengths may and do occur 

 in the various species of Oxalis, but 

 individual plants of the same species 

 may have either all long-, short-, or 

 mid-styled blossoms. This peculiarity 

 of the genus has been known for over 

 a century, and numerous examples 

 are to be found in Nicholas Joseph 

 Jacquin's Monograph of the Oxalis, 

 a quarto volume with eighty-one 

 plates (mostly coloured), published 

 at Vienna in 1794. 



Very few of the Wood Sorrels, 

 tuberous or otherwise, are really 



389 



