Morphology and Ontogeny of Foliar Sclereids in Olea europaea. II. Ontogeny

• Published in: American journal of botany Vol. 40; no. 10; pp. 745 - 752
• Main Author: Arzee, Tova
• Format: Journal Article
• Language: English
• Published: American Botanical Society 01-12-1953
• Subjects: Cell growth; Cell nucleus; Epidermal cells; Epidermis; Mesophyll cells; Mother cells; Ontogeny; Parenchyma; Plant growth; Sclereids
• ISSN: 0002-9122; 1537-2197
• DOI: 10.1002/j.1537-2197.1953.tb06550.x

Development of sclereids takes place in young leaves which have attained an approximate size of 3-5 mm. in width and 10 mm. in length. Two types of sclereids were distinguished in the lamina: "type I," "T"-shaped sclereids originating in the palisade parenchyma; "type II," polymorphic sclereids originating in the spongy parenchyma. The process of sclereid ontogeny in Olea seems comparable to the development of sclereids in a number of investigated plants. The sclereid initials originate in the parenchyma of expanding leaves and are first distinguishable from the rest of the parenchyma cells because of their enlarged nuclei. The most distinctive feature of the sclereids is their excessive degree of growth as compared with neighboring cells; this results in the remarkably large size of adult sclereids. During their extension, the main tips and branches intrude between the neighboring cells. Both "symplastic" and "intrusive growth" seem to be involved in sclereid development, as only a combination of these two methods appears to explain the establishment of the new intercellular relationships which occur during the course of sclereid development.