Vessel

vessel

1. a passenger or freight-carrying ship, boat, etc.

2. an aircraft, esp an airship

3. Anatomy a tubular structure that transports such body fluids as blood and lymph

4. Botany a tubular element of xylem tissue consisting of a row of cells in which the connecting cell walls have broken down

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vessel [′ves·əl]

(botany)

A water-conducting tube or duct in the xylem.

(engineering)

A container or structural envelope in which materials are processed, treated, or stored; for example, pressure vessels, reactor vessels, agitator vessels, and storage vessels (tanks).

(naval architecture)

Any craft that can carry people or cargo over the surface of the water.

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Vessel 

(also trachea), in plants, a conducting element of xylem that consists of a long hollow tube formed by a single row of cells (vessel members) perforated on their transverse walls. Vessels are characteristic of angiosperms (except for certain Polycarpicae [Trochodendron, drimys] and Liliaceae [lily of the valley, dracena, agave]); they also occur in some ferns (Pleridium), selaginella, Equisetum, and Gneticae (ephedra, Gnetum, Welwitschia).

Vessels may be annular, helical, scalariform, or pitted, depending on the structures of their lateral walls. In annular and helical vessels the secondary membrane resembles rings or twisted ribbons. The vessels arise in the early stages of the development of plant organs and are capable of extension. Scalariform and pitted vessels with larger deposits of secondary membrane and bordered pits in the walls are formed in organs that have finished growing lengthwise. After the lignification of the membranes, the cell protoplasts die and the cavity of the vessel fills with water.

Primitive vessels were characterized by great length (reaching 1.3 mm) and small diameter; the lateral walls were marked by scalariform porosity (tulip tree), and the angular cross section of vessel members had scalariform perforations on sloped transverse walls. Highly specialized vessels are composed of short vessel members that in cross section are rounded and have a wide opening (reaching 0.5 mm in diameter). The vessel members have simple perforations on the transverse walls and small alternate pits on the lateral walls (ash, oak).

L. I. LOTOVA