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SECRETORY RESERVOIRS (DUCTS) OF TWO KINDS IN GIANT RAGWEED (AMBROSIA TRIFIDA; ASTERACEAE)
Author(s) -
Lersten Nels R.,
Curtis John D.
Publication year - 1988
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.1537-2197.1988.tb14192.x
Subject(s) - biology , petiole (insect anatomy) , phloem , xylem , botany , bract , raceme , pith , stele , inflorescence , petal , hypocotyl , asteraceae , vascular bundle , anatomy , hymenoptera
Two types of tubular secretory reservoirs occur in Ambrosia trifida , the first such example known in plants. Paraffin and resin sections, and clearings showed that, although each type consists of many separate unbranched tubes, they differ in anatomy, secretory contents, distribution, and length. Reservoirs (PAR) containing a red substance (presumably a polyacetylene) and lined with a biseriate epithelium parallel the largest leaf and stem vascular bundles. One PAR arises near the base of each leaf lobe midrib and extends through the petiole to the node or continues in the stem cortex to the node below. Other PARs start at the cotyledonary node or in cotyledons and extend down into the primary root, where they have only a single layer of unspecialized epithelium. PARs realign themselves, and more form de novo, until the primary root has two to four separate arrays of PARs abutting the endodermis, each with three to six parallel PARs. Branch roots have similar PAR arrays but unconnected to PARs of the parent root. Inflorescence PARs occur only in bracts, and in petals of male flowers. The second type of reservoir (OR) has a uniseriate epithelium and contains an unidentified oil. ORs occur in phloem, and in pith next to xylem, of stem and large leaf bundles. They dwindle in successively smaller veins until the two smallest orders lack them. ORs occur only in phloem in the hypocotyl; none occur in cotyledons, roots, or floral parts.