LABORATORY 12

ANGIOSPERMS: STEMS AND ROOTS

Division AnthophytA

In this lab you will observe the specific tissues that define the roots and stems of vascular plants. True vascular plants have three important organs: roots, stems, and leaves. You will observe both monocot and dicot stems, young and old stems, and softwood and hardwood stems. There are excellent pictures in you textbook and figures in your Photographic Atlas. Look up the textbook references, pictures, and atlas photographs and record in the spaces below. As before, prepare to draw the specimens that you observe under the microscope. Label with the vocabulary provided for each slide. Follow the embedded links and print out the drawings associated with stems and roots.

Plan to return to the lab to review these slides during Open Lab. Think through the tissues and their functions. Doing so will not only help you prepare for the laboratory exam, it will also help you prepare for your lecture examination. Remember, the same vocabulary is common to BOTH lecture and lab. Practice using the new plant vocabulary with your laboratory partners also. Use your laboratory instructor as a resource! Take the time to locate and record the page numbers from the current editions of your text and photo atlas. Have these page numbers recorded BEFORE coming to the lab. Remember – next week we will be outside for part of the lab doing tree identification. Please dress accordingly and be prepared for cooler temperature or rain..

ROOTS

1 Slide: Allium root tip, l.s.

This is an apical meristem. You observed this same slide last semester while studying cell division. Why? Sketch the root tip and label the root cap and the regions of division, elongation, differentiation, and maturation. What is the function of the root cap? Refer to Figures ____and ____ in Campbell. Atlas figures __________.

2 Slide: Ranunculus root c.s.

Sketch the root and label epidermis, cortex and cortical parenchyma with starch, phloem, cambium, xylem vessel, pericycle, endodermis, and sclerenchyma. Refer to Figure ____. Atlas figure _____, and _____.

3 Slide: Triticum root hairs

Label epidermal cell and root hair. How do root hairs compare with leaf trichomes functionally and structurally? Atlas figure _____

4 Lateral transport of minerals and water in root

Study Figure _____ to describe how water and minerals are moved from outside the root to the xylem for conduction to the leaves. There is no microscope slide here. Write a paragraph in your laboratory report describing the two routes by which water, minerals, and other chemicals can enter the root’s stele.

5 Slide: Salix lateral root origin

Salix is the genus of the weeping willow. This slide shows the initiation of one or more lateral roots from a layer of meristematic tissue called the pericycle. Refer to Figure ____ in Campbell.

6 Slide: Sclerids (Stone cells)

This slide is a cross section of a pear’s parenchyma. Look carefully for the "grit" within the fleshy storage area. This grit is composed of sclerenchyma.

7 Root Model

Note the regions and special features on the model that you observed microscopically.

8 Plastomount of root types

Name several different types of roots (tap, fibrous, modified tap, prop, aerial…) and give one plant example of each. Atlas figures______.

Link to Root Types

STEMS

1 Slide: Coleus stem tip

Label young leaf, apical meristem, tunica, corpus, provacsular strand. Indicate the four regions: division, elongation, differentiation, maturation.). Refer to Figure ______ in Campbell. Atlas Figure ____

2 Slide: Helianthus

This is the common sunflower which is a dicot. Note the characteristic arrangement of vascular bundles. Label the epidermis, collenchyma, cortex, sclerenchyma, cambium, xylem vessel, and pith. Refer to Figure ____ in Campbell.

3 Slide: Zea mays

This is corn which is a monocot. What sort of leaf venation does corn have? Note the arrangement of vascular bundles in this monocot. Draw the stem and label epidermis, cortex, xylem (pitted, annular, and spiral), bundle sheath, and phloem. Refer to Figure _____ in Campbell. Atlas Figure _______. How can you tell immediately by looking at the stem if a plant is a monocot?

4 Slide: Cucurbita stem - l.s., c.s.

This is the genus of the common cucumber. In this stem, locate the important features of phloem: sieve tubes, slime plug, sieve plate, and companion cell. Examine BOTH the l.s. and the c.s. Draw both c.s. and l.s. in your lab report. Refer to Figure _____in Campbell.

5 Slide: Tilia stem

This is a three-year-old woody dicot stem. Sketch the stem and label cork, collenchyma, endodermis, phloem ray, phloem fibers, vascular cambium, cork cambium, wood rays, annual ring (spring and summer wood), wood fiber, pith. Refer to Figure _____. Also study Figure _____ in Campbell: Production of secondary xylem and phloem by the vascular cambium. Also study Figure _____: Anatomy of a tree trunk. Atlas figures _____ and _____.

6 Model:  Monocot Stem

Note the regions and special features on the model that you observed microscopically. Compare the monocot stem model and the dicot stem model.

7 Model:  Dicot Stem

Note the regions and special features on the model that you observed microscopically. Compare the dicot model with the monocot model.

8 Stem types and modified stems

Stolons, rhizomes, tubers, bulbs, etc. Refer to Figure ___ in Campbell. Atlas Figure ____: tuber, tendril, corm, bulb, and rhizome.

LINKS to     Stem Habit Types Stems and Buds Underground Stems

TERMINOLOGY

stele	xylem	cork cambium
cortex	phloem	summer wood
root hair	epidermis	spring wood
xylem	parenchyma	stolons
phloem	collenchyma	tuber
pericycle	sclerenchyma	rhizomes
endodermis	vascular cambium	corm