Structural attributes of the hypogeous holoparasite Hydnora triceps Drège & Meyer (Hydnoraceae)

The morphology of the hypogeous root holoparasite Hydnora triceps is highly reduced, and as with many holoparasites, the vegetative body is difficult to interpret. The vegetative body of H. triceps has been historically considered a "pilot root" studded with lateral appendages known as &qu...

Full description

Saved in:
Bibliographic Details
Published in:American journal of botany 2007-09, Vol.94 (9), p.1439-1449
Main Authors: Tennakoon, Kushan U, Bolin, Jay F, Musselman, Lytton J, Maass, Erika
Format: Article
Language:English
Subjects:
anatomy
Anatomy and Morphology
Cambium
Endosymbionts
haustoria
holoparasite
Holoparasites
homeosis
Hydnora
Hydnoraceae
Parasite hosts
Parasites
parasitic plants
Plant morphology
Plant roots
Plants
Vascular bundles
Xylem
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The morphology of the hypogeous root holoparasite Hydnora triceps is highly reduced, and as with many holoparasites, the vegetative body is difficult to interpret. The vegetative body of H. triceps has been historically considered a "pilot root" studded with lateral appendages known as "haustorial roots." We found the vegetative body of H. triceps to consist of a rhizome with a thickened root-cap-like structure that covered a vegetative shoot apical meristem. From the apical meristem, procambial strands originated and developed into endarch collateral vascular bundles arranged radially around a pith without an interfascicular cambium. Xylem vessels had scalariform pitting and simple perforation plates. A continuous periderm without root hairs was observed. Increase in girth was attributed to cork and fascicular cambia. "Haustorial roots" or bumps on the surface of the vegetative body were exogenous, contained meristems and were the origins of vegetative branching, budding, and haustoria. The haustoria of H. triceps were cylindrical and penetrated the host root stele. Phloem and xylem elements were observed within the endophyte, and direct xylem to host-xylem contacts were observed. The arrangement of vascular tissues and xylem anatomy of H. triceps are likely plesiomorphic features in light of Hydnoraceae's placement in the Piperales.
ISSN:0002-9122
1537-2197
DOI:10.3732/ajb.94.9.1439