|The trunk of this Pigafetta palm growing|
in Papua New Guinea, develops its full
thickness at the top, as the massive leaf
|Palms like this Ptychosperma develop many|
upright stems from a branching
underground rhizome system.
|Philodendron selloum achieves some modest|
height by supporting its stem with prop roots.
|The screw pine (Pandanus) is a monocot with |
long strap-shaped leaves and a fibrous
trunk similar to that of palms. It supports itself
with prop roots
|This giant Pandanus in a New Guinea forest |
has prop roots six inches thick.
Another approach to tree-ness is seen in bananas and some gingers. What appears to be a trunk is actually mostly the concentric cylindrical bases of the leaves (the leaf sheathes). Each new leaf that pushes up through the center of this false stem (pseudostem) has a longer cylindrical base than the previous, and so can achieve the proportions of a modest tree. The true vertical stem rises through the center of the pseudostem only when it is time to flower and fruit.
|The herbaceous pseudostem of a banana shoot|
builds up as each tubular leaf sheath that
pokes up through the center is longer than
the previous one.
|Banana "trees" are really giant herbs. The soft shoots|
bud off of an underground rhizome system and die
|Papyrus shoots arise from underground rhizomes through the|
elongation of a single internode at the base of the globe-shaped
cluster of leaves and flowers. From Kerner and Oliver, The
Natural History of Plants, 1904.