Comparative Morphology and Molecular Systematics of African Podostemaceae‐Podostemoideae, with Emphasis onDicraeanthusandLedermanniellafrom Cameroon

The Podostemaceae (eudicots, Malpighiales) are adapted to rivers that exhibit distinct high‐low water seasonality, mainly in the tropics. They attach to submerged rocks with ribbonlike or crustose green roots that cover the substrate like a carpet. Pronounced root dorsiventrality resulted in disklik...

Full description

Saved in:
Bibliographic Details
Published in:International journal of plant sciences 2007-02, Vol.168 (2), p.159-180
Main Authors: Moline, P., Thiv, M., Ameka, G. K., Ghogue, J.‐P., Pfeifer, E., Rutishauser, R.
Format: Article
Language:English
Subjects:
Biological taxonomies
Flower buds
Flowers
Genera
Leaves
Ovaries
Parsimony
Plant morphology
Plant roots
Taxa
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The Podostemaceae (eudicots, Malpighiales) are adapted to rivers that exhibit distinct high‐low water seasonality, mainly in the tropics. They attach to submerged rocks with ribbonlike or crustose green roots that cover the substrate like a carpet. Pronounced root dorsiventrality resulted in disklike crusts lacking root caps. African Podostemoideae show a bewildering array of forms not known from other flowering plants, such as (i) foliage leaves having a basis with two sheaths (e.g.,Ledermanniella linearifolia), (ii) modular shoot construction with repeated stem cups (Ledermanniella ledermannii), (iii) endogenous origin of flowers along stems (Dicraeanthus africanus), and (iv) epiphyllous flowers (Ledermanniella letouzeyi). Important morphological transformations specific to African podostemoids include a shift from erect to inverted flowers in the spathella and unilocular ovaries arising via septum loss. NewmatK sequence data and new morphological data for eight African Podostemaceae species of the generaDicraeanthus,Djinga, andLedermanniellaare combined with previously published sequences representing all major groups to test the placement of the African taxa in the family. All podostemoids studied from continental Africa form a clade that is sister to the Madagascan generaEndocaulosandThelethylax. The sister of this African‐Madagascan lineage is the clade comprising all Asian podostemoids and the American genusPodostemum, whereas all other New World podostemoids and the subfamily Tristichoideae are more basal.
ISSN:1058-5893
1537-5315
DOI:10.1086/509607