Morphology of Flowering Plants Test - 7

• Roots developing from plant parts other than radicle are adventitious roots because adventitious means coming from outside. That means they develop in places other than their natural position.
• They may arise from stems, leaves etc. Example: oak trees

So, the correct option is 'Adventitious'.

► Fusiform roots have tapering on both ends.Radish has tapering too on both sides hence they are fusiform roots.

► Napiform root: Turnip
► Conical root: Carrot
► Tuberous root: Sweet potato

Nodulated Roots: The roots  having  the irregular or the round mass or a lump called nodules within the cells are known as nodulated roots.The roots of leguminous plants possess these characteristic swelling nodules which are caused by colonies of nitrogen fixing bacteria (Rhizobium).

Turnip is a root vegetable. So we eat the root of turnip. Therefore the edible part of turnip is the root. Turnip, carrot has modified root and potato, turmeric, ginger has modified stem to store food.

Stilt root helps in support of plant and is not for food storage.

The stem is the ascending part of the axis bearing branches, leaves, flowers and fruits. It develops from the plumule of the embryo of a germinating seed. It bears nodes and internodes.

Root hairs in plants have large surface area and is surrounded by water soil and nutrients and due to large surface area root hairs absorb water for the growth of plants.

The short lateral stem called the offset in some aquatic plants (such as Eichhornia) bears leaves and tufts of roots at the node and gives rise to new plants.

• The stem is normally divided into nodes and internodes. Rhizome of ginger is a modification of stem because it bears nodes and internodes.
• Rhizome is a modified stem of a plant that is usually found underground, often sending out roots and shoots from its nodes.
• Rhizomes are also called as creeping root stalks. Rhizomes develop from axillary buds and are diageotropic or grow perpendicular to the force of gravity. The rhizome also retains the ability to allow new shoots to grow upwards.

Thus, the correct answer is option B.

• Phylloclade is found in Opuntia and Cactus. Phylloclades and cladodes are modified branches. They are flattened structures that are photosynthetic and resemble leaf-like branches. 
• They store water inside the tissue. The leaves are modified into spines. 

Thus, the correct answer is option D.

The Blade, or lamina, is the broad, flat part of the leaf. Photosynthesis occurs in the blade, which has many green food-making cells.

• Nodulated roots are found mainly on legume plants and they form a symbiotic relationship with nitrogen-fixing bacteria.
• The pea plant, Pisum sativum, is a legume plant that has nodulated roots.
• The pea belongs to the family Fabaceae or Leguminosae.

Hence, the correct answer is option A: Leguminosae.

Pneumatophores are short, vertical and negatively geotropic roots that occur in mangrove plants. Plants having pneumatophores grow in salty marshes. They have lateral roots that grow upward into the air from horizontally secondary roots. These are called as halophytes.

Thorns, spines and prickles are modifications in plants that act as defensive organs and prevents them from attack from various insects.

• Bulbs are underground buds with the stem reduced to small discs on which short, fleshy storage leaves grow. These leaves are enclosed by thick scales.
• Bulb scales morphologically are the continuous sheathing leaf bases.
• Bulbs are produced by monocotyledon plants in which the usual structure is modified for storage and reproduction. The outer scales are dry and inner scales are generally fleshy and contain reserve food material.
  Example: Onion.

Venation refers the to pattern of arrangement of veins in the leaflet. The monocots have their leaf veins arranged in a parallel manner with respect to each other whereas in case of dicots the the leaf veins are reticulate or muzzled up.

The placenta is attached to the developing seed near the hilum.

Grass is the correct option because veins on the lamina run parallel to one another is called parallel venation. It is characteristically found in moncot plants and grass is a characteristic of moncot plant.

• A modified stem that is flattened and capable of unlimited growth is called as phylloclade. It carries out photosynthesis. It is a xerophytic adaptation. Leaves are changed into spines in xerophytic structures called phylloclade.
  Examples include Opuntia.
• Opuntia is a xerophytic plant, in which leaves are modified into spine to reduce the rate of respiration.
• A modified stem capable of limited growth is called as cladode. It carries out photosynthesis. Examples include Ruscus, Asparagus species.
• Phyllode is a petiole modified into a leaf-like structure. Thus, the correct answer is 'Phylloclade.'

Reticulate venation is a characteristic of dicots and parallel venation is of monocots. But few exceptions are also seen in this generalization parallel venation is also found in dicotplants.
Example: Calophyllum, corymbium , etc., and reticulate venation is also found in monocot plants such Alocasia, Smilax, etc. 

Verticillaster is a special type of inflorescence seen in Leucas. At each node of the stem two axillary opposite cymose inflorescences develop on either side. The cyme in the axil of each leaf, starts as a dichasial cyme but subsequently become monochasial scorpioid cyme. As a result, the cyme bends round the stem on either side and meets a similar cyme from the opposite side. Hence, at each node there is a cluster of flowers completely surrounding the stem. It is a characteristic of family Labiatae. 

► Cucurbitaceae family shows axillary solitary inflorescence. 
► Thyrse inflorescence is a characteristic of Rubiaceae family. 
► Capitulum inflorescence is a characteristic of family Asteraceae. 

Therefore, the correct answer is option D.

Cyathium inflorescence consists of a single central female flower surrounded by many groups of male flowers. In each group the male flowers are borne in scorpiod manner and the inflorescence is surrounded by an involucre.
Example: Euphorbia.

Capitulum (Head): It is a modified raceme in which the main axis is flattened, called receptacle.

• A biparous cyme ending in uniparous cyme constitutes the verticillaster. Verticillaster inflorescence is an inflorescence in which the flowers are arranged in a seeming whorl, consisting in fact of a pair of opposite axillary, usually sessile, cymes, as in many mints.
• A verticillaster is a fascicle with the structure of a dichasium; it is common among the Lamiaceae. Many verticillasters with reduced bracts can form a spicate (spike-like) inflorescence that is commonly called as a spike.

Flowers are sessile in spike. A spike is an unbranched, indeterminate inflorescence, similar to a raceme but bearing sessile flowers (sessile flowers are attached directly, without stalks). Examples occur on Malabar nut (Justicia adhatoda) and chaff flowers. 

It is acropetally because since the plant continues to grow it's clockwise arrangements gives the maximum absorption of light for photosynthesis and help the plant to form buds for it's upgrowth.

Capitulum (Head): It is a characteristic of compositae (Asteraceae). Peduncle is flattened to form receptacle that bears centripetally arranged small sessile flowers called florets surrounded by involucre of bracts.
Example: Marigold, Sunflower.

• Hypanthodium has a flask-shaped fleshy receptacle which possesses a narrow canal and a terminal pore at one end. The pore is surrounded by a few scales while the canal is lined by downwardly pointed hairs.
• Internally the receptacle bears male flowers towards the pore and female flowers towards the base. Sterile, neuter or gall flowers occur in between the two groups.
• The inflorescence is formed by the condensation of three types of flower- bearing axes (cymose groups).
• Hypanthodium is found in the genus Ficus of the family Moraceae, e.g., Peepal (Ficus religiosa), Banyan (Ficus bengalensis), and Fig (Ficus carica).

• The peduncle is the main axis of an inflorescence or the axis bearing a flower or fruit.
• Thalamus is the thickened part of a stem from which the flower organs grow in angiosperms.
• The petiole is the cylindrical stalk that joins the leaf base with the leaf blade or lamina.
• The pedicel is a stem that attaches a single flower to the inflorescence. 

Hence, the correct answer is option B: Peduncle.

• Umbel in which the main axis is reduced very much and all flowers appear to be arising from the same point. At the base of flowers, cluster of bracts form an involucre. It is type of racemose inflorescence. Example is hydrocotyle.
• Cymose in which the main axis terminates into a flower and hence has a limited growth. In cymose inflorescence the flowers are borne in a basipetal order. Examples are begonia, oak and Solanum.
• Capitulum or head bears many sessile and small florets. The main axis becomes flat and called receptacle. It is type of racemose inflorescence. Example is sunflower.
• Verticillaster is a cluster of sessile or subsessile flowers borne on a dichasial ending in monochasial cyme in the form of condensed whorl on either side of the node. Example is tulsi.

Hence, the correct answer is option A: Umbel.