Rosaceae Ann Bond March 15, 2001

Rosaceae Taxonomy Class Magnoliopsida Subclass Rosidae Order Rosales Family Rosaceae –4 Subfamilies : Spiraeoideae Maloideae Rosoideae Prunoideae

Floral Formula: CA 5 CO 5 A ˜ G 1 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

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 hypanthium Hypanthium-floral tube formed from the receptacle Androecium: many Fruits: Accessory: pome Spur shoots- a short branch bearing fruit buds

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: drupes Stipules- paired appendages sometimes located at the base of leaf petiole.

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, hip Stolons-modified, elongated, horizontal stems that creep along the ground. They root at the nodes or tip to give rise to new plants.

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: 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

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 Harris, James G. and Harris, Melinda Woolf. Plant Identification Terminology. Spring Lake Publishing: Spring Lake, Utah Jones, Samuel and Luchsinger, Arlene. Plant Systematics. McGraw-Hill, Inc: New York, New York Wood, Marcia. “Strawberry Growers Test Methyl Bromide Alternatives” ARS. Vol 49, No 1, January, 2001.