Agriculture Reference
In-Depth Information
Rhizome branches
developed
from lateral buds
Shoot developed from
apical bud
Node
Internode
Adventitious roots
Contractile root
Remains of last year's rhizome
Figure 7.16
Structure of a bearded
Iris
rhizome
which grow just above the ground and root at nodes
along the stem or at stem tips producing plantlets.
These are often found in rosette plants and grow
from buds at the base of the plant. The term
stolon
is often used interchangeably with runner but it also
includes plants such as
Rubus fruticosus
(bramble)
(Figure 7.15g) which have long arching branches
which root where their tips touch the ground. Non-
perennating rhizomes can be a nuisance when trying
to eradicate perennial weeds such as
Calystegia
sepium
and
Convolvulus arvensis
(hedge and field
bindweed) and
Elymus repens
(couch grass) (Fig. 7.17)
as their rhizomes can penetrate up to 5 m deep and
they can regenerate a new plant from buds on even
the tiniest section.
Suckers
are stems that grow from adventitious buds
(buds which do not derive from the plumule (see p.
106), which are found on the roots of many plants,
such as
Rhus typhina
(stag's horn sumach). These
can be useful in propagating plants vegetatively but
can also be a nuisance if their spread is difficult to
control.
developing shoot
dormant bud
adventitious roots
Figure 7.17
Couch grass (
Elymus repens
) rhizome
exposure to light since stems can photosynthesize
but roots cannot, hence the need to 'earth up'
potatoes to exclude light.
Anemone blanda, A. coronaria
De Caen Group,
Begonia
x
tuberhybrida
(tuberous begonia),
Gloxinia
and
Cyclamen
tubers develop from the hypocotyl and
are often classed as stem tubers.
Rhizomes and stem tubers can also be methods
of vegetative (asexual) spread. Others include the
runners
of
Fragaria
spp. (strawberry)
,
horizontal stems
