Question

Psammophytes are plants growing on ____________ type of soil.
a. Alluvial
b. Sandy
c. Alkaline
d. Acidic

Answer 1

Any feature of an organism or its part, which enables it to exist under its habitat conditions, is termed adaptation. Every organism develops certain adaptations so does the population or a community. Adaptations prevent destruction of organism’s vital vegetative tissues and help in large production.

Complete answer: In 1895 Warming classified plants into several ecological groups on the idea of their requirements of water and also on the idea of nature of substratum on which they grow.
Warming classified plants on the idea of nature of substratum (soil) into five groups:

1. Plants of acidic soil (Oxylophytes)
2. Plants of saline soil (Halophytes)
3. Plants growing on the sand (Psammophytes)
4. Plants growing on the surface of rocks (Lithophytes)
5. Plants growing within the crevices of rocks (Chasmophytes).

On the idea of water requirement and nature of soils, the plants are classified as follows:

Hydrophytes: Plants growing in or near water.
Xerophytes: Plants adapted to survive under the condition of very poor supply of accessible water within the habitats. Places where available water isn't present adequate quantity are termed xeric habitats.
Mesophytes: Plants growing in an environment which is neither very dry nor very wet.
Hydrophytes: Plants which grow in wet places or in water either partly or wholly submerged are called hydrophytes or aquatic plants. Examples are Wolffia, Lemna, etc.

Xerophilous plants are further classified on the premise of their habitats as follows:

(1) Habitats physically dry (where water retaining capacity of the soil is incredibly low and therefore the climate is dry, e.g., desert, rock surface, waste land, etc.).

(2) Habitats are physiologically dry (places where water is present in excess amounts but it's not likely to be absorbed by the plants easily. Such habitats could also be too salty or too acidic, too hot or too cold). Habitats dry physically similarly as physiologically, e.g., slope of mountains.

(3) Xerophytes are characteristic plants of desert and semi-desert regions, yet they will grow in mesophytic conditions where available water is in sufficient quantity. These plants can withstand extreme dry conditions, low humidity and extreme temperature.

Xerophytes are categorized into several groups in line with their drought resisting power.
These groups are as follows:

1. Drought escaping plants: These xerophytes are short-lived. During dry periods they survive within the kind of seeds and fruits which have hard and resistant seed-coats and pericarps respectively. At the arrival of favourable conditions seeds germinate into new small sized plants which complete their life cycles within some weeks’ time. The seeds become mature before the dry condition approaches. In this way, plants remain unaffected by extreme conditions. Examples—(Papilionatae), some inconspicuous compositae (e.g., Artemisia) and members of families Zygophyllaceae, Boraginaceae, some grasses, etc.

2. Drought enduring plants: These are small sized plants which have capacity to endure or tolerate drought.

3. Drought resistant plants: These plants develop certain adaptive features in them through which they'll resist extreme droughts. Xerophytes grow on a spread of habitats. Some grow on rocky soils (Lithophytes) some in deserts, some on the sand and gravels (Psammophytes) and a few may grow on the waste lands (Eremophytes). Some plants of xeric habitat have water storing fishy organs, while some don't develop such structures.

Psammophytes: They are the plants that thrive in shifting sands, primarily in deserts. They have a variety of adaptations that enable them to exist on wind-blown sands. In such an environment, the plants are often covered with sand, or their rootage is exposed. It’s also difficult for the seeds to germinate. Psammophytic trees and shrubs form strong adventitious roots on those parts of their trunks buried within the sand (Haloxylon persicum, Calligonum); adventitious buds and, then, shoots arise on the exposed roots (Ammondendron, Eremosparton, Smirnowii).

Therefore, the answer is b, sandy.

Note:
Many psammophytes are annual ephemerals. Perennial psammophytes have small, very reduced leaves or no leaves at all; photosynthesis and transpiration are accomplished by the stem. The fruits have appendages within the shape of wings (Haloxylon), propellers (Ammondendron) or parachutes (Aristida) that enable them to maneuver with the sand and to stay on the sun's surface. After seed germination (usually in early spring), the roots grow very quickly, soon reaching a depth of roughly 0.5 m. Also, psammophytes are often used to stabilize sandy soils.