Stem Function and Anatomy

Question 1

shoot

Answer 1

a stem and its leaves

Question 2

stem functions

Answer 2

• conducting water, minerals, organic molecules between roots and leaves
• supporting leaf weight
• move leaves toward light, away from shade
• withstand mechanical stressors
• storage and reproduction in specialized stems

Question 3

all tissue systems arise during ____

Answer 3

embryogenesis

Question 4

dicot/monocot seeds

Answer 4

monocot - one cotyledon
dicot - two cotyledons

Question 5

seed structures

Answer 5

hypocotyl - stem
radicle - roots
cotyledon - leaves
plumule - embryonic shoot
not true stem, roots, leaves

Question 6

meristems

Answer 6

small populations of rapidly proliferating cells that produce all mature organs of a vascular plant

Question 7

shoot apical meristem (SAM)

Answer 7

• increase stem length through cell division
• located at primary stem tip
• dormant before growing season
• often protected by bud scales and leaf primordia (embryonic leaves)

Question 8

axillary buds

Answer 8

stems grow outwards, forming leaves, flowers, branches from meristems in axillary buds

Question 9

common features of plant stems: internode, node, axillary buds, stipules

Answer 9

internode - space between leaf attachment points

node - where leaves are attached to stems

dormant axillary buds - located between stem and leaf petiole, become branches, leaves, or flowers

stipules - paired, leaf-like appendages at base of leaf

Question 10

specialized stems: rhizomes, tubers, tendrils, stolons, bulbs, corms, cladophylls

Answer 10

rhizomes - horizontal stems that grow underground and have long to short internodes (irises, grasses, ferns)

tubers - underground stems that store food (potato); “eyes” are nodes (axillary buds)

tendrils - specialized stems used for fastening to surfaces (cucumber)

stolons (runners) - horizontal stems that grow above group and have long internodes (strawberries); vegetative reproduction

bulbs - large buds w fleshy leaves attached to short stem (onions, tulips)

corms - resemble bulbs, but are almost entirely made up of stem tissue, w papery leaves (crocus)

cladophylls - flatten, leaf-like stems (orchids, prickly pear cactus)

Question 11

vascular tissue (stele) in primary stems history

Answer 11

prostele in earliest plants
siphonosteles evolved from protosteles
eusteles (includes atactostele)

Question 12

protostele

Answer 12

-solid xylem core, phloem surrounding xylem
-some SVPs

Question 13

siphonostele

Answer 13

-tubular xylem and phloem, with pith
-common in ferns (SVPs)

Question 14

eusteles

Answer 14

-have discrete vascular bundles of xylem and phloem
-dicots (angiosperms) and gymnosperms
-vascular bundles (phloem out, xylem in)

Question 15

bicollateral bundle

Answer 15

“sandwiched together”
-ex xylem between upper phloem and lower phloem (cs)

Question 16

atactostele

Answer 16

stele of monocot angiosperms
- vascular bundles scattered throughout ground tissue
- no distinct pith or cortex
- variation of eustele (discrete)

Question 17

atactostele vascular bundles

Answer 17

typical monocot vascular bundle consists of two large vessels with smaller ones, an air space, sieve tubes, and companion cells
- bundle surrounded by sclerenchyma sheath