NEW ZEALAND FERNS 51 



To understand how forest conditions could be detrimental, the 

 ecology of T. barbata must be briefly considered. So far as possess- 

 ing a trunk is concerned it is a tree-fern, but, unlike most of its 

 congeners, this trunk is not tall, slender, and crowned by a few 

 fronds spreading umbrella like. On the contrary the trunk is 

 short, massive, and, so far as New Zealand examples go, 8 not 

 noticeable without a close examination, owing to the fronds being 

 very numerous and crowded into a somewhat globular mass (see 

 fig. 1). Such plants may be some 1.8 m. in diameter and 1.2 to 

 1.5 m. tall. The fronds put one closely in mind of Osmunda regalis 

 L. They are 90 cm. long, more or less, the upper vertical, the 

 lower semi-vertical, the stripe rather shorter than the blade and 

 the pinnae bright or yellowish green, rather glossy, thick, coria- 

 ceous, opaque, and rather hard. The fern then is, at any rate, 

 sub-xerophytic, and in consequence it never occurs in the forest 

 but either grows mixed with Leptospermum scoparium Forst., a 

 xerophytic shrub or small tree, of ericoid form, or in open places 

 in the Leptospermum heath exposed to the full sunshine and but 

 little sheltered from wind. Between heath and forest an ecolog- 

 ical contest is always in progress, xerophytic conditions favouring 

 the former formation and mesophytic the latter. 9 



The fossil species Osmundites Dunlopi and 0. Gibbiana were 

 found in the extreme south of the South Island. Osmundites 

 Dunlopi is considered by Kidston and Gwynne-Vaughan as related 

 to Todaea barbata, and 0. Gibbiana to the wide-spread Osmunda 

 regalis. 10 



The two endemic New Zealand species of Leptopteris, L. superba 

 and L. hymenophylloides, though so closely related to Todaea, 

 demand absolutely different life conditions. Their fronds are of 

 a true hymenophyllaceous character, being only a few cells thick 

 and without stomata a true epidermis or intercellular spaces, 



8 There is nothing approaching Australian examples with their trunks a ton and 

 a half in weight. (See also remarks by Cheeseman in Manual of the New Zealand 

 Flora, p. 1024, Wellington, 1906.) 



9 Cockayne, L., A botanical survey of the Waipoua Kauri Forest, pp. 30-31. 

 Wellington, 1908. 



10 Osmunda regalis does not occur in either Australia or New Zealand. The 

 record by H. C. Field in Ferns of New Zealand, pp. 145-147 cannot be accepted. 



