Rosaceae: Characters and Affinity | Dicotyledons | Botany

In this article we will discuss about:- 1. General Characters of Rosaceae 2. Floral Formula of Rosaceae 3. Number and Distribution 4. Range of Floral Structures 5. Common Plants 6. Affinity and Economic Importance.    

General Characters of Rosaceae:

Plants—herbs, shrubs or trees (e.g., Apple Pear, Cherry, Plum, Loquat, etc.), sometimes climbing, often prickly. Leaves—alternate usually pinnately compound, stipulate (adnate stipules). Inflorescence—cymose. Flowers—regular (but sometimes zygomorphic, as in Chrysobalanus), usually bisexual (unisexual in Aruncus), perigynous sometimes epigynous, with odd sepal posterior.

Sepals—usually 5, connate to receptacle imbricate. Petals—5 to ∞, free, imbricate. Stamens—free (but monadelphous in Chrysobalanus), usually nume­rous, in 1-many whorls of 5 stamens, sometimes 5 or 10; bent inwards in bud, perigynous (but epigynous in Pyrus, Eriobotrya). Carpels—1 (e.g., Prunus) to numerous, free or united; ovary superior or inferior (e.g., Pyrus), 1-celled or 2-5 celled, usually with 2 pendulous or ascen­ding, anatropous ovules. Fruit—drupe, pome or aggregate of folli­cles or achenes or berries. Seed—generally without endosperm. Embryo—plano-convex, often with fleshy cotyledons.

Floral Formula of Rosaceae:

Number and Distribution of Rosaceae:

This family consists of about 115 genera and 3,200 species which are chiefly found in it temperate regions (in India in the Northern Himalayas).  

Range of Floral Structures in Rosaceae:

This family has wide range of variation in the construction of flowers regarding the structure of receptacle, union of carpels and the nature of fruit. It has been divided into six subfamilies according to the floral construction by Focke.

Subfamily I. Spiraeoideae:

The receptacle is somewhat flat but never forms a deep cup or convex structure. Stamens—10-many. Carpels—5, free, situated in the centre of the receptacle. Fruit—a follicle or capsule. Example —Spiraea, found in the Eastern Himalayas.

Floral Formula:

Subfamily II. Pomoideae:

The flowers are usually epigynous. The receptacle is deeply con­cave. Stamens—many. Carpels—2-5, more or less united and adnate to the cap of the receptacle (inferior ovary); each carpel contains two ovules. Fruit—a pome. Examples—Pyrus malus L. (Apple), Cotoneaster, etc.

Floral Formula:

Subfamily III. Rosoideae:

The receptacle is deeply concave in nature. Stamens—many. Carpels—many and free, situated in the cup-shaped receptacle, as in Rosa, or the receptacle is swollen and convex, or slightly elongated, as in Rubus, on which many free carpels are seated. Each carpel contains 1 or 2 ovules. Examples—Rosa alba L., a common garden rose, Potentilla fulgens L. found in the Eastern Himalayas, Fragaria vesca L. (Strawberry), Rubus hexagynous Roxb. (Bramble), etc.

Floral Formula:

Subfamily IV. Neuradoideae:

The receptacle is cup-shaped, enlarging in fruit. Carpels—5-10, united at the base of the receptacle. Example—Neurada procumbens L. found in the desert of India.

Floral Formula:

Subfamily V. Prunoideae:

Flowers regular. The receptacle is somewhat cup-shaped. Stamens —10-20 or more. Carpel—1, contains two pendulous ovules. Style— terminal. Fruit—drupe. Examples—Prunus, etc.

Floral Formula:

Subfamily VI. Chrysobalanoideae:

Flowers irregular. The receptacle is deeply cup-shaped. Stamens —10-15 or more; filaments are united (monadelphous). Carpel— one; ovules erect; style basal. Fruit—berry. Examples—Chrysobalanus, etc.

Floral Formula:

Common Plants of Rosaceae:

(1) Cabbage-rose (Rosa centifolia L.), Wild rose of Bengal (R. involucrata Roxb.), R. damascena Mill., commonly cultivated for attar, R. indica L., (Syn. Rosa chinensis Jacq.), a small spreading shrub fre­quent in gardens, White rose (R. alba L.).

(2) Cherry (Prunus cerasus L.).

(3) Plum (P. domestica L.).

(4) Apricot (P. armeniaca L.).  

(5) Peach (P. persica Benth. & Hook. f.).

(6) Hudson Almond (P. amygdalis L).

(7) Prunus bokhariensis Royle.

(8) Prunus puddum Roxb. = P. ceraslodes D. Don., very common in the hills.

(9) Apple (Pyrus malus L.) (Syn. Malus sylvestoris (L.) Mill.

(10) Pear (P. communis L.)

(11) Loquat (Eriobotrya japonica Lindl.), a small tree cultivated for its delicious fruits.

(12) Indian strawberry (Fragaria nilgerrensis Schldl.) and Strawberry (F. vesca L.) are trailing herbs commonly found on the hills.

(13) Pygeum acuminatum Coleb., a tree.

(14) Potentilla supina L.,P fulgens L. and P. nepalensis Hook, are annual herbs commonly found in Darjeeling, Shillong and other hilly stations.

(15) Bramble (Rubus hexagynous Roxb.), a climbing shrub with flat prickles.

(16) Blackberry (Rubus fruticosus L.), a sub-erect rambling shrub, com­monly found in the Himalayas.

Affinity and Economic Importance of Rosaceae:

This family is closely allied to Ranunculaceae from which it is readily distinguished by the presence of stipules, usual perigynous flower and cyclic arrangement of stamens. It is distinguished from Leguninosae by the position of odd sepal.

Economic Importance of Rosaceae:

This family is of great importance from economic point of view. Most of the members are fruit-producing plant. Frageria vesca pro­duces strawberry, Pyrus malus yields apple. Pear is obtained from Pyrus communis; Prunus armeniaca and P. persica yield apricot and peach respectively. Almonds are obtained from the seeds of Prunus amygdalis. Many plants are useful for ornamental purposes, such as, Spiraea, Cotoneaster, Crataegus, Rosa, Potentilla, Prunus, etc.