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ONTOGENY AND COMPARATIVE ANATOMY OF THORNS OF HAWAIIAN LOBELIACEAE
Author(s) -
Carlquist Sherwin
Publication year - 1962
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1962.tb14959.x
Subject(s) - biology , trichome , ontogeny , botany , anatomy , genetics
C arlquist , S herwin . (Claremont Graduate School, Claremont, Calif.) Ontogeny and comparative anatomy of thorns of Hawaiian Lobeliaceae. Amer. Jour. Bot. 49(4): 413–419. Illus. 1962.—Species of Rollandia and Cyanea (sections Genuinae and Palmaeformes), endemic Hawaiian genera of Lobeliaceae, are unique in the family in possessing thorns and thorn‐like structures on leaves, and in some cases, on stems and flowers. These thorns always originate in conjunction with a unicellular, non‐glandular trichome which terminates the thorn. Ontogenetic studies show that divisions leading to the formation of the thorn occur in the ground meristem as soon as the trichome is differentiated. Periclinal divisions predominate at first, but anticlinal and diagonal ones are also present at all stages. Thick secondary walls are formed on the trichome and other epidermal cells near the thorn tip. Periderm forms on old thorns of stems. Vascular tissue and laticifers are absent in thorns. Thorns in Cyanea and Rollandia seem best interpreted as specializations within these genera.