164 Transactions. 



Leaves opposite, decussate, sessile or with short knob-like petioles closely 

 appressed to the stem ; each pair of leaves about |-| in. apart ; leaves 

 standing out from the stem at an angle of 30° usually, but varying to 80° ; 

 J— § in. long, j— j in. broad ; some lower leaves bend downwards at the tip, 

 many are flat, others slightly hollow on upper surface ; ovate in shape, 

 varying from elliptic-oblong to almost orbicular, ending in a blunt point ; 

 thick, coriaceous, only a mid-vein apparent, upper surface smooth or with 

 few hairs, under-surface thickly covered with silky white appressed hairs. 



Flowers in heads at the top of the branches, at the very tip or in the 

 axil of a topmost branch. Flowers sessile, white ; perianth cylindrical with 

 spreading limbs, covered with silky hairs ; four perianth leaves ; stamens 

 two, seated upon the perianth, opposite the two outer lobes ; ovary superior ; 

 one carpel, one ovule ; stigma capitate, style brownish-red. Fruit a berry, 

 white, fleshy. 



(c.) Leaf -anatomy. 



Epidermis : Dorsal surface — cells irregular, thick-walled ; stomata fre- 

 quent, irregularly disposed, sunken ; thick cuticle. Beneath the upper 

 epidermis is a layer of very large colourless cells, probably for water-storage. 

 Ventral surface — cell - walls thick, cells somewhat polygonal in shape, 

 stomata numerous, clefts pointing in all directions, sunken cuticle present ; 

 numerous long hairs, unicellular, thick-walled, secreting rather sticky fluid. 



Chlorenchyma only slightly differentiated ; cells rounded, upper layers 

 not definitely palisadic, rather loosely arranged ; lower cells loose, forming 

 sort of spongy mesophyll ; air-spaces on both surfaces beneath stomata. 

 Patches of water-storage cells alternating with vascular bundles. 



(d.) Conclusion. 

 Pimelea arenaria is always a plant of semi-stable dunes, and its growth- 

 form, with small leaves growing close together, and the whole plant procum- 

 bent and close-growing, is typically xerophytic. The leaf is xerophytic in 

 certain anatomical characters — e.g., in having thick cuticle, thick-walled 

 epidermis, sunken stomata, water-storage cells, under-surface protected by 

 hairs — yet mesophytic in other respects, especially in the important point 

 of chlorenchyma structure. 



10. Leptospermum scoparium. 



(a.) Habitat. 

 Very common on stable dune, and especially Upon heath plains ; it 

 forms close brown patches of varying size, interspersed among Cassinia 

 fulvida, Discaria toumatou, Carmichaelia subulata, Leptocarpus simplex, and 

 Scirpus nodosus. On the fixed plains towards the southern end of the beach 

 the manuka is rather more stunted in height, and forms large patches, 

 sometimes near patches of the bracken fern (Pteridium esculentum). At the 

 northern end the manuka is commonly found in the vicinity of standing 

 water. Besides occurring on dunes, L. scoparium is the dominant heath 

 plant of New Zealand. It occurs also in swamps, bogs, and on rocks. 



(b.) Growth-form,. 



A stunted or erect brownish shrub, varying in size and shape, with 

 spreading, leafy branches ; from 1-| ft. to 3 ft. high, sometimes forming con- 

 siderable colonies. 



Stems woody, brown, much branched. 



