21 3 Roots and Stems KEY CONCEPT Roots

21. 3 Roots and Stems KEY CONCEPT Roots and stems form the support system of vascular plants.

21. 3 Roots and Stems Roots anchor plants and absorb mineral nutrients from soil. • Roots provide many functions. – support the plant – absorb, transport, and store nutrients – root hairs help absorption

21. 3 Roots and Stems • There are several parts of a root. – root cap covers the tip root cap

21. 3 Roots and Stems • There are several parts of a root. – root cap covers the tip – apical meristem is an area of growth apical meristem

21. 3 Roots and Stems • There are several parts of a root. – root cap covers the tip – apical meristem is an area of growth – vascular cylinder contains xylem and phloem vascular cylinder

21. 3 Roots and Stems • There are two main types of roots. – Fibrous root systems have fine branches. – Taproot systems have one main root. Fibrous root Taproot

21. 3 Roots and Stems support plants, transport materials, and provide storage. • Stems have many functions. – support leaves and flowers – house most of the vascular system – store water Baobab trees Cactus

21. 3 Roots and Stems support plants, transport materials, and provide storage. • Stems have many functions. – support leaves and flowers – house most of the vascular system – store water – grow underground for storage Ginger rhizomes Potato tubers

21. 3 Roots and Stems support plants, transport materials, and provide storage. • Stems have many functions. – support leaves and flowers – house most of the vascular system – store water – grow underground for storage – form new plants Strawberry stolons

21. 3 Roots and Stems • Some stems are herbaceous and conduct photosynthesis.

21. 3 Roots and Stems • Some stems can be woody, and form protective bark.

21. 3 Roots and Stems • Primary growth increases a plant’s length. • Secondary growth increases a plant’s width.

21. 3 Roots and Stems • Tree rings help determine the age of a tree. bark bands heartwood one year of growth sapwood

21. 3 Roots and Stems Root hairs anchor plants and help them absorb water and minerals by A. B. C. D. Protecting the growing part of the root Producing more xylem and phloem Increasing the root’s surface area Lengthening the tips of roots

21. 3 Roots and Stems Where is the vascular cylinder of a root? A. B. C. D. Covering the tip Just behind the root cap In the center of the root Inside the meristem

21. 3 Roots and Stems What are the two basic forms of roots? A. B. C. D. Fibrous roots and taproots Long taproots and short taproots Fine-branched roots and thick-branched roots Vascular cylinders and meristems

21. 3 Roots and Stems Divisions of a plant’s apical meristem cells produces A. B. C. D. Primary growth Secondary growth Ring growth Lateral meristem growth

21. 3 Roots and Stems What can you infer from a thick annual ring inside a thin annual ring in a tree trunk? A. B. C. D. Low precipitation followed by high precipitation A short ring followed by a very cold winter secondary growth followed by primary growth Good conditions followed by harsher conditions