lecture 6 grasses

Question 1

Three Characteristics of a Grass

Answer 1

1. The flowers lack petals and are borne between bracts in a leafless inflorescence
2. The leaves are flat, long and slender, and form a sheath around the stem
3. The stems are round, generally hollow, and somewhat swollen at the nodes

Question 2

The current system of plant taxonomy is based primarily on ___________

___________,more than any other character, that really define the grass species

Answer 2

reproductive structures
flowers

Question 3

Grasses are difficult to identify because many of their ___________and ____________structures are unique to the family

Answer 3

reproductive and vegetative

Question 4

How Grass Plants Are Put Together (Vegetative Structures)

All grasses are ______________ plants (or _________)

This means that grasses have only one _________, which is the first or “______” leaf that emerges from a seed

Answer 4

monocotyledonous; monocots
cotyledon; seed

Question 5

the first structure that emerges from a grass seed is a cylindrical, tube-like structure called a ________

it is from within this tube that the fragile cotyledon grows upward to the surface and unfurls

Answer 5

coleoptile

Question 6

As the grass plant continues to grow,______________, each of which emerges from within the leaf that preceded it

Answer 6

leaves are formed

Question 7

The characteristics of the _______ are commonly used for grass identification

Answer 7

blades

Question 8

Characteristics of blades

Answer 8

– Blade width

– Whether the expanded blade is rolled or flat

– Whether or not the midrib is distinctly visible on the upper surface

– Presence or absence of hairs

– Whether newly emerging blades are rolled or folded

Question 9

The ______ or ________ part of the leaf (the part that wraps around the stem) is termed the ______

Answer 9

“tube” or “sleeve”
sheath

Question 10

Commonly used sheath characteristics:

Answer 10

– The degree to which the sheath is open (the edges merely overlapped) or closed (the edges fused together into a seamless sleeve) and the

– Presence or absence of hairs

Question 11

The entire leaf, then, extends upwards from a ______, up the sheath, and outward to the tip of the blade

Answer 11

node

Question 12

The ____________ and _________ are also important characteristics = ________ of the leaf

Answer 12

structures at the junction of the blade and sheath
collar of the leaf

Question 13

Two types of structures that grasses may have in this region

Answer 13

– Auricles

– Ligules

Question 14

_______ are finger-like projections of the upper edges of the sheath that appear to wrap around the stem

The ______ or ______ of these paired structures is a useful identification feature

Auricles may be _______, _______, or _______ and ________ or fringed with hairs

Answer 14

auricles
presence or absence
short,long, or absent and smooth

Question 15

_________ are small projections located between the blade and the stem

To best observe this structure, _____________________, and it will pop into view

Answer 15

ligule

gently pull the blade away from the stem

Question 16

The ligule may be:

Answer 16

• completely membranous
• a ring of hairs
• hairs that form a fringe on a membranous base

Question 17

The type of ligule, as well as its _______, __________, and ___________ of the leading edge are key identification features

Answer 17

length, overall shape, amd texture

Question 18

Reproductive structures

Individual flowers of grass plants are called _______
A typical floret has __________ and a ________ with _________ at the tip

Answer 18

florets
three stamens and a single ovary with two stigma

Question 19

The ovary is borne between _______________

– The outer bract is the _________

– The usually smaller, inner bract is the _________

These structures are usually green when the plant is in flower, becoming ______ to ________ as the seed ripens

Answer 19

two tiny, leaf-like bracts
lemma
palea
chaffy to leathery

Question 20

The ________, ________, and _________ of the palea and lemma help in identification

In addition, lemmas are frequently

Answer 20

length, texture and number of major veins (nerves)
awned

Question 21

Florets may be borne _______, or in clusters of up to ____ or more

These clusters of florets are termed _________, each with two additional bracts at the base

These bracts are the ______, which may be variously awned and nerved

Answer 21

singly; 14
spikeletes
glumes

Question 22

Spikelets will break away from the stem or disarticulate in one of two ways:

Answer 22

– Above the glumes, leaving the empty glumes on the plant after the spikelets have dropped

– Below the glumes, in which case the glumes remain attached to the spikelet as it drops

Question 23

Inflorescence
A _________ inflorescence is anywhere the spikelets are not sessile or individually pediceled on the main axis.

A ________ inflorescences are those in which the spikelets are sessile on the central axis or rachis.

A _________ inflorescence has pedicels supporting single spikelets, with the pedicel attached to the central axis.

Answer 23

panicle
spike
raceme

Question 24

Eleusine indica (L.) Gaertn.

Answer 24

Goose grass/Paragis/bila-bila

Question 25

Saccharum spontaneum L.

Answer 25

Wild sugarcane/ talahib

Question 26

Imperata cylindrica (L.) P.Beauv

Answer 26

Cogon grass

Question 27

Saccharum officinarum

Answer 27

Sugar cane

Question 28

Axonopus compressus (Sw.) P.Beauv.

Answer 28

Carabao grass

Question 29

Cymbopogon nardus (L.) Rendle.

Answer 29

Citronella grass

Question 30

Bambusa blumeana

Answer 30

Kawayang tinik

Question 31

Zea mays (L.)

Answer 31

Corn

Question 32

Oryza zativa (L.)

Answer 32

Rice

Question 33

Coix lacryma-jobi L.

Answer 33

Job’s tears/ adlai