02 Morphology - Copy - PLS 172 Lecture 2 1 of 11 MORPHOLOGY...

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PLS 172 Lecture 2 1 of 11 MORPHOLOGY, STRUCTURE, GROWTH AND DEVELOPMENT Mikal E. Saltveit, Dept. Plant Sciences, UC Davis TABLE OF CONTENTS Topic page Methods of classification 1 Cellular structure 2 Anatomy 5 Morphology 8 Growth and development 8 Horticultural vs. physiological maturity 9 Importance of developmental stage 9 References 9 METHODS OF CLASSIFICATION Horticulture encompasses an extremely large number of fruits, vegetables and ornamentals. Our first problem in studying such a diverse assemblage is to find a means of classifying them into groups on the basis of their post- harvest responses. What grouping would segregate horticultural commodities on the basis of similar post- harvest characteristics? Crops can be classified in a number of ways. For example, they can classified by taxonomic criteria (e.g., ontogeny, anatomy, or morphology), by geographical origin (e.g., temperate, sub-tropical, or tropical), by growing season (e.g., cool vs. warm season), by repro- ductive life cycle (e.g., annual, biannual, perennial), by part that is used (e.g., root, stem, leaves), or by method of propagation (e.g., seed, cutting). Some of these classifications are helpful; others are not. A botanical classification is of little value from the postharvest standpoint since commodities that belong to the same family, genus, or specie often have very dif- ferent postharvest responses (Table 1). Table 1. Taxonomic classification of some horticultural crops. Family Genera Species Crops Roseaceae Apple & rose Liliaceae Asparagus & lily Leguminosae Pea & bean Solanaceae Solanum Eggplant & potato Cruciferae Brassica oleracea Cauliflower & kale Cucurbitaceae Cucurbita pepo Pumpkins & summer squash Horticultural crops can also be classified into tradi- tional groups (Table 2), however, the most useful method of classification is to group crops by plant parts because commodities within these groups usually have similar postharvest characteristics (Table 3). Table 2. Subgroups of horticultural crops within gen- eral groups. Vegetables Root and tubers Bulbs Leafy and Succulents Fungi Fruit (Immature and mature) Seedlings Fruit Small fruit and berries Tropical and subtropical Deciduous tree fruit (e.g. Pome, Stone fruits) Nuts and seeds Legumes Tree nuts Ornamentals Flowers Foliage Nursery stock Table 3. Grouping horticultural commodities by plant part used. Plant part Common example Entire plant Sprouts, potted plants Stem Asparagus, kohlrabi Root Primary Carrot, turnip Secondary Sweet potato, cassava Tuber Potato, yam, dahlia Bulbs Onion, tulip, daffodil Leaf Leaf blade Leaf lettuce, spinach Petiole Celery, rhubarb Buds Lettuce, cabbage Flora parts Immature Broccoli, cauliflower, artichokes Mature Cut flowers Fruits Fleshly Immature Cucumbers, summer squash Mature Apples, tomatoes, grapes, citrus Non-Fleshly Immature Sweet corn, okra, green beans Mature Seeds and nuts CELLULAR STRUCTURE The plant cell is the basic unit that goes into building all higher plants. All vascular plants are made up of many millions of cells working together. A plant cell is not
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