Page 2 Plant-Bacteria Interactions Edited by Iqbal Ahmad, John ...

292j 15 The Use of Rhizospheric
Figure 15.2 Elastoplasticity of morphology of water hyacinth. (a)
Swollen petioles and (b) elongated petioles.
growing conditions (Figure 15.2). In crowded conditions, the float is not produced
but a long petiole develops [55,87]. The leaf blade is orbicular to ovoid in shape and
the size also varies with growing conditions [55,87]. The roots are adventitious,
fibrous and unbranched and have a conspicuous root cap. The roots produce many
laterals but are usually small in size and vary with growing conditions. This gives
them a fine feathery appearance. Root length varies from 10 to 300 cm. They are
usually whitish in color but turn pinkish violet because of the presence of anthocyanin
when exposed to light [87]. The inflorescence of the water hyacinth is a spike
with 4–25 yellow-spotted lavender-colored flowers. The fruit is a many-seeded
capsule.
15.4.3
Ecology
Water hyacinth is a perennial, tropical, aquatic weed. It grows in a variety of freshwater
habitats ranging from shallow temporary ponds, marshes and sluggish flowing
waters to large lakes, reservoirs and rivers [87]. The plants can survive on wet
mud for prolonged periods or perennate in the form of seeds [55,87]. The plants exist
within a wide range of temperatures from as low as 1 C during winter in northern
latitudes to over 40 C during summer in dry tropics [87]. They can also survive in
soils poor in nutrients, even in water highly polluted with a variety of organic and