Pegg. — Ecological Study of New Zealand Sand-dune Plants. 165 



Leaves about. J in. long, j^h m - broad, varying in shape, lanceolate or 

 ovate, ending in a sharp point, sessile, rigid, thick, underside convex with 

 midrib apparent, otherwise leaf apparently veinless ; dotted, usually spread- 

 ing ; brown in colour. 



Floivers : Solitary, sessile, in axil of group of leaves or at end of branch ; 

 usually |— | in. diameter. Calyx-tub? brown, top-shaped, ending in five 

 small brownish-white membranous lobes. Petals white, spreading, with a 

 small claw, almost orbicular, ^ in. or more in diameter, with brownish veins. 

 Stamens numerous in a ring around the top of the perianth-tube. Ovary 

 semi-inferior, usually with five carpels, multilocular, with numerous linear 

 slightly curved seeds in each loculus. Stigma capitate, almost peltate. 

 Fruit a capsule, brown, woody, persistent, with persistent calyx-tube forming 

 a rim around it. 



(c.) Leaf -anatomy . 



Epidermis : Cells thick-walled, rounded, square, rectangular or poly- 

 gonal in shap^ (surface view) ; above the glands there are two long cells 

 surrounded by a ring of smaller cells. Cuticle thick on both surfaces. 

 Upper surface, no stomata ; on under-surface stomata numerous, irregularly 

 arranged, prominent as regards epidermis, but sunk beneath the cuticle. 



Chlorenchyma differentiated ; two or more layers of palisade cells on 

 upper surface, spongy mesophyll in the middle, and palisade cells on the 

 underside ; cells loosely arranged, with intercellular spaces, and air-spaces 

 adjacent to stomata. Large glands containing aromatic oil, embedded in 

 the chlorenchyma just beneath th a epidermis on both sides of the leaf. 

 Stereome in two patches, above and below each vascular bundle. 



Fibro-vascular bundle? : About three seen in transverse section in the 

 chlorenchyma with stereome, and parenchyma sheath. In transverse section 

 of the woody stem, the large polygonal pith cells in the centre contained 

 round starch grains, .some of the cells staining deeply, others scarcely at all. 



(d.)JConclusion. 



Leptospermum scoparium exhibits the following xerophytic characters : 

 Small sfcifj leaves, relatively thick, thick cuticle on both surfaces, thick- 

 walled epidermis, stomata only on under-surface, palisade tissue on both 

 sides of the leaf, stereome developed in vascular bundles. With regard to 

 its growth-form the following quotation from Cockayne* is instructive : 

 " Leptospermum scoparium Forst. (Myrtac.) may be a moderate-sized tree, a 

 tall shrub, a dwarf plant 2-8 cm. tall which flowers and ripens seed, and 

 an absolutely prostrate plant which forms a dense covering to the ground 

 and puts forth adventitious roots, although the erect forms are exceeding 

 difficult to artificially strike as cuttings." Its varied habitats are for the 

 most part xerophytic, so that its leaf-anatomy, considered along with the 

 variety of growth-forms, may in general be considered epharmonic. 



11. Epilobium Billardierianum. 



(a.) Habitat. 

 Found in moist sand-hollows. 



(6.) Groivih-form. Figs. 1 to 3. 



A small herb with the lower part of the stem rather woody and low- 

 growing, from which arise several stolons running along the ground and 



* Trans. N.Z. Inst., vol. 44, p. 14. 



