THE UPRIGHT HABIT 



29 



Osmundaceae, which link so naturally on to the early fossil Botryopterideae. 

 The living Marattiaceae also provide good examples. In the latter it is the 

 direct continuation of the growth of an embryo erect from the first: but in 

 the Osmundaceae the embryo is prone, and its apex turns upwards later. 



Lin hahit ij{ Blechmim tabiilare, S. Brazil, 

 in Christ, after Wacket.) 



It is the same upright habit which leads to the dendroid types. Given 

 continuous apical growth a vertical axis becomes an upright column. Dwarf 

 examples of this are seen in the Blechnums (e.g. B. tahdare. Fig. 35). Con- 

 tinued further a "Tree Fern" is the result, whose trunk may bear 60 feet or 

 more above the ground a huge basket-shaped group of leaves surrounding 

 the apical bud. A practical limit of height is imposed by the mechanical 



