Morpho-anatomical studies on the change in the foliage of two imbricate-leaved New Zealand podocarps: Dacrycarpus dacrydioides and Dacrydium cupressinum

• Published in: Plant systematics and evolution Vol. 302; no. 1; pp. 41 - 54
• Main Authors: Dörken, Veit M, Parsons, Robert F
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.01.2016; Springer-Verlag GmbH; Springer Nature B.V
• Subjects: adults; Anatomy; Animal cuticle; Biomedical and Life Sciences; Cotyledons; Dacrycarpus; Dacrycarpus dacrydioides; Dacrydium cupressinum; Drought; Epidermis; Foliage; Gymnosperms; habitats; Hypodermis; juveniles; Leaves; Life Sciences; mature plants; Mesophyll; Morphology; New Zealand; Original Article; Parenchyma; Phosphorus; Plant Anatomy/Development; Plant Ecology; Plant Sciences; Plant Systematics/Taxonomy/Biogeography; Plant tissues; rain; Rainfall; Resin canals; Seedlings; soil; trees; Vascular bundles; New Zealand; Leaf; Anatomy; Morphology; Scleromorphy
• ISSN: 0378-2697; 1615-6110; 2199-6881
• DOI: 10.1007/s00606-015-1239-5

Many extant gymnosperms have strongly reduced leaves. While this is usually treated as adaptation to drought, other habitat factors must also be involved. This subject and the related change from juvenile needle leaves to adult imbricate leaves are poorly understood. Here we explore these topics by describing the leaf morphology and leaf anatomy of seedlings and adult plants of Dacrydium cupressinum and Dacrycarpus dacrydioides. In both species, the cotyledons, primary leaves, and juvenile leaves are needle like. Then D. dacrydioides foliage becomes partly imbricate. In D. cupressinum, the needle leaves gradually become smaller and more close-set, with some fully imbricate leaves appearing on old trees. It follows from very high rainfall and low soil phosphorus of the habitat that their very small leaf size is likely to be a scleromorphic character, not a xeromorphic one. Confusion in the literature in the use of scleromorphy and xeromorphy is pointed out and clarified.