the soil surface and give rise to vertical shoots from axillary buds • s tolons that function as “runners” along the soil surface giving rise to new plantlets • tubers that serve as storage “sinks” for carbohydrates Root Rhizome Rhizomes Stolons Stolo Tubers
Leaf Structure & Function Leaves are the primary photosynthetic organs. Petiole Axillary bud Leaflet Compound leaf Petiole Axillary bud Simple leaf Leaf structures include: • one or more blades • a stalk called a petiole that connects the leaf to a stem • simple leaves have 1 blade • compound leaves have multiple blades called leaflets • veins that have a branched (dicots) or parallel (monocots) arrangement
Storage leaves Stem Evolutionary Adaptations of Leaves Leaves can be modified for a variety of functions: • tendrils which cling to larger support structures • spines to repel herbivores • bulbs that store nutrients • reproductive leaves that detach and give rise to a new plant (asexual) Spines Tendrils Reproductive leaves
3 Basic Plant Tissue Types Dermal tissue • outer, protective covering of the plant Vascular tissue • transports water, nutrients & gives structural support Ground tissue • everything else! Dermal tissue Ground tissue Vascular tissue each of these tissues forms a continuous tissue system throughout the plant There is also a type of undifferentiated tissue called meristem which we will address later in this chapter.
More on Dermal Tissue… In nonwoody plants and structures (e.g., leaves) the dermal tissue is epidermis. • epidermis is frequently covered with a waxy cuticle to minimize water loss • some plants also have trichomes in epidermal tissue which provide protection from water loss, intense light and insects In woody plants the epidermis develops into a protective laver called periderm (part of the bark). Trichomes 300 μ m