Rosaceae

Ann BondMarch 15, 2001

Rosaceae Taxonomy

• Class Magnoliopsida• Subclass Rosidae• Order Rosales• Family Rosaceae

– 4 Subfamilies:• Spiraeoideae• Maloideae• Rosoideae• Prunoideae

Floral Formula:

CA5 CO5 A˜ G1 or G˜ or G 5

Leaves: Alternate, simple, or compound

leaves that have paired stipules

Rosaceae Characteristics

Habit: Trees, shrubs and herbs; mainly in the

north temperate zone

Inflorescences: Solitary flowers; can have

racemose and cymose clusters

Rosaceae Characteristics

Spiraeoideae

• Important genera: Spirea (Bridal Wreath)

• Shrubs with white, yellow, pink, or red flower

• Leaves: simple, alternate, short petioles, without stipules

Spiraeoideae

• Infloresences: umbel-like raceme, corymbs, or panicle

• Gynoecium: superior ovary, apocarpous (separate) of 1-8 carpels

• Androecium: many

• Fruits: follicle capsule

Spiraeoideae

Spiraeoideae

Spiraeoideae

Maloideae

• Important genera: Pyrus (pear), Malus (apple), Sorbus (Mt. Ash)

• Small, branching, deciduous shrubs and trees

• Leaves: simple or pinnately compound, toothed, with stipules

Maloideae

• Infloresences: cyme or corymb• Gynoecium: inferior ovary, syncarpous (fused) of

2-5 carpels, ovary adnate to hypanthiumHypanthium-floral tube formed

from the receptacle• Androecium: many• Fruits: Accessory: pomeSpur shoots- a short branch

bearing fruit buds

Maloideae

Maloideae

Maloideae

Maloideae

Prunoideae

• Important genera: Prunus (almond, cherry, nectarine, peach, apricot, and plum)

• Trees and shrubs (generally small); showy white or pink flowers

• Leaves: simple with stipules

Prunoideae

• Infloresences: corymb, umbel, raceme• Gynoecium: superior ovary, 1 pistil,

hypanthium not adnate to ovary• Androecium: many• Fruits: drupesStipules- paired appendages

sometimes located at the base of leaf petiole.

Prunoideae

Prunoideae

Rosoideae

• Important genera: Rubus (raspberry), Rosa (rose), Potentilla (cinquefoil), Fragaria (strawberry)

• Upright or climbing shrubs, often with thorny stems; stolons or runners in Fragaria

• Leaves: compound(pinnate, palmate, or alternate) with stipules

Rosoideae• Infloresences: solitary, corymb, raceme• Gynoecium: superior ovary, 10 or more pistils

(each pistil becomes a simple fruit)• Androecium: many• Fruits: aggregate accessory: achene, drupe, hipStolons-modified, elongated, horizontal

stems that creep along the ground. They root at the nodes or tip to give rise to new plants.

Rosoideae

Rosoideae

Rosoideae

Rosoideae

Rosoideae

Rosoideae

Fruits of the Rosaceae: General

• Pericarp: the wall of the ovary in fleshy fruits

• The thickness of the pericarp increases just prior to pollination and fertilization

• The pericarp consists of 3 layers:– Exocarp: outer layer of the pericarp– Mesocarp: middle layer; often fleshy– Endocarp: inner layer of pericarp

Fruits: Spiraeoideae

• Usually a follicle (sometimes called a capsule)• Follicle-simple, dry

fruit developed from a single pistil that dehisces along one margin

• Importance-the plants of this subfamily are used as ornamentals

Fruits: Maloideae

• Pome is predominant fruit in this subfamily

• Pome-simple accessory fruit with more than one carpel– There are several seeds

– Accessory fruits are derived from non-ovarian tissue

– Apples, pears, and chokeberries hang from their pediuncle

• Importance- fruits are used for fresh eating, processing, and plants are used as ornamentals

Fruits: Maloideae

Fruits: Maloideae*

Fruits: Prunoideae

• Drupes are the predominant fruit• Drupe- a stone-fruit

having a hard inner pit that contains one seed and a fleshy outer layer

• Importance: the edible fruits of this subfamily are used for fresh eating and processing

Fruits: Prunoideae*

Fruits: Prunoideae*

Fruits: Rosoideae

• Achene, hip, and druplets

• Achene-dry one seeded fruit with a firm close fitting wall– Pericarp is free from the seed– Strawberry is considered a aggregate fruit of

achenes.– Each pistil becomes a fruit and the receptacle

swells and surrounds the fruit

Fruits: Rosoideae

Fruits: Rosoideae

• Hip- an aggregation of achenes surrounded by the receptacle plus hypanthium; considered an accessory fruit

• Druplets-a cluster of fruits clearly traceable to separate pistils of the same flower and inserted on a common receptacle– The receptacle swells and surrounds the fruits

• Importance- fruits are eaten fresh and used for pies

Fruits: Rosoideae*

The Future of Rosaceae

References

• Brickell, Christopher and Zuk, Judith. The American Horticultural Society, A-Z Encyclopedia of Garden Plants. DK Publishing: New York, New York. 1997.

• Harris, James G. and Harris, Melinda Woolf. Plant Identification Terminology. Spring Lake Publishing: Spring Lake, Utah. 1997.

• Jones, Samuel and Luchsinger, Arlene. Plant Systematics. McGraw-Hill, Inc: New York, New York. 1985.

• Wood, Marcia. “Strawberry Growers Test Methyl Bromide Alternatives” ARS. Vol 49, No 1, January, 2001.