Procambial Initiation for the Vascular System in the Shoot ofAlstroemeria(Alstroemeriaceae, Liliales)

Procambial Initiation for the Vascular System in the Aerial Shoot of Costus(Costaceae, Zingiberales)

“…An ideal way to analyze procambial generation in the monocotyledonous shoot is to consider it as a union of superposed disks of insertion (Sharman 1942;Hitch and Sharman 1968;Pizzolato 2002Pizzolato , 2004Pizzolato , 2006. A disk of insertion is the segment of the shoot axis bearing the base or attachment of a leaf.…”

“…Zimmermann and Tomlinson (1967, 1972, in the Arecaceae and Juncaceae, observed procambia to differentiate basipetally from some isolated sites but acropetally in continuity from other sites of origin. Hitch andSharman (1968, 1971) and Pizzolato (2002) described isolated, bidirectional procambial differentiation in Poaceae. Pizzolato (2004Pizzolato ( , 2006 saw similar differentiation in the Alstroemeriaceae and Commelinaceae.…”

“…Hitch andSharman (1968, 1971) and Pizzolato (2002) described isolated, bidirectional procambial differentiation in Poaceae. Pizzolato (2004Pizzolato ( , 2006 saw similar differentiation in the Alstroemeriaceae and Commelinaceae. However, students of these last three monocot families caution that procambial isolation is so brief that it leads to an impression of continuous acropetal differentiation through the disks of insertion.…”

“…However, students of these last three monocot families caution that procambial isolation is so brief that it leads to an impression of continuous acropetal differentiation through the disks of insertion. In order to stress the bidirectionality of procambial differentiation from isolated sites in the disks of insertion of the Poaceae, Pizzolato (2002) referred to this type of differentiation as dot-to-dot linkages. This term also stresses that a procambial strand consists of several initially isolated procambial segments.…”

“…Procambial traces are not established for a particular leaf. Any trace that arises near enough in time and site to a particular leaf primordium is a candidate to become a procambial trace for that leaf (Zimmermann and Tomlinson 1972;Pizzolato 2002Pizzolato , 2004Pizzolato , 2006. There is agreement that some procambial traces for a leaf are initiated before the leaf primordium appears at the apex (Priestley et al 1935;Simpson and Philipson 1969;Zimmermann and Tomlinson 1972).…”