PCA Weeds Study Guide Exam
PCA WEEDS (CATEGORY E) — COMPLETE 100-QUESTION
PRACTICE EXAM
SECTION 1: WEED BIOLOGY AND IDENTIFICATION
1. Which of the following characteristics is most useful for identifying Yellow
Nutsedge (Cyperus esculentus)?
• A) A square stem
• B) A triangular stem in cross-section
• C) Opposite leaf arrangement
• D) Ligules consisting of a fringe of hairs
Answer: B
Rationale: Sedges are characterized by "sedges have edges," meaning their stems
are distinctly triangular in cross-section. This distinguishes them from grasses,
which have round or flattened stems, and broadleaves, which have square or
round stems.
2. A "winter annual" weed is best described as a plant that:
• A) Germinates in the spring and dies in the winter
• B) Germinates in the fall, overwinters as a rosette, and seeds in the spring
• C) Lives for three or more years
• D) Only grows in high-altitude environments
Answer: B
Rationale: Winter annuals, such as Common Chickweed and Shepherd's Purse,
,germinate when temperatures drop in the fall, grow slowly through the winter as
a low rosette, and complete their life cycle (flowering and seeding) by late spring
or early summer before dying.
3. Which structure allows Johnsongrass (Sorghum halepense) to spread
vegetatively and persist as a perennial?
• A) Bulbs
• B) Stolons
• C) Rhizomes
• D) Taproots
Answer: C
Rationale: Johnsongrass is a highly invasive perennial weed that spreads via
aggressive underground stems called rhizomes. This makes it difficult to control
because the plant can regrow even if the above-ground portion is destroyed by fire
or mowing.
4. Barnyardgrass can be distinguished from other summer annual grasses by its
lack of:
• A) A root system
• B) Seeds
• C) A ligule and auricles
• D) Chlorophyll
Answer: C
Rationale: Barnyardgrass (Echinochloa crus-galli) is one of the few common grass
weeds that lacks both a ligule and auricles at the leaf collar. This characteristic is a
key identifying feature that separates it from foxtails and crabgrasses.
,5. The term "ephemeral weed" refers to a plant that:
• A) Lives for exactly one year
• B) Completes multiple generations in a single growing season
• C) Lives for 100 years
• D) Only grows in aquatic environments
Answer: B
Rationale: Ephemeral weeds, such as Annual Bluegrass (Poa annua), can complete
their entire life cycle in just a few weeks and produce multiple generations within
one growing season, making them difficult to control.
6. A biennial weed completes its life cycle in:
• A) One year
• B) Two years
• C) Three years
• D) Four or more years
Answer: B
Rationale: Biennials, like Common Mullein and Wild Carrot, require two years. The
first year is vegetative growth (a rosette), and the second year they bolt, flower,
produce seed, and die.
7. The cotyledon (seed leaf) shape of a broadleaf weed seedling is important for
identification because:
• A) It determines the herbicide to use
• B) It helps distinguish between species at the early growth stage
, • C) It affects the soil pH
• D) It indicates the weed's native origin
Answer: B
Rationale: Cotyledon shape, size, and color are often the first visible characteristics
of a seedling and can be used to identify weed species before true leaves develop,
which is critical for early post-emergence herbicide decisions.
8. Which of the following is a characteristic of a monocot weed?
• A) Net-veined leaves
• B) Fibrous root system
• C) Two cotyledons
• D) Branching taproot
Answer: B
Rationale: Monocots (grasses, sedges, and lilies) have fibrous root systems,
parallel-veined leaves, and one cotyledon. Broadleaf weeds (dicots) have net-
veined leaves, taproots, and two cotyledons.
9. The leaf collar of a grass plant is the:
• A) Tip of the leaf blade
• B) Junction where the leaf blade meets the sheath
• C) Root system
• D) Flower head
Answer: B
Rationale: The leaf collar is the region on the outside of the leaf where the blade
joins the sheath. It is a key identification feature because it may have a ligule,
auricles, or neither.
PCA WEEDS (CATEGORY E) — COMPLETE 100-QUESTION
PRACTICE EXAM
SECTION 1: WEED BIOLOGY AND IDENTIFICATION
1. Which of the following characteristics is most useful for identifying Yellow
Nutsedge (Cyperus esculentus)?
• A) A square stem
• B) A triangular stem in cross-section
• C) Opposite leaf arrangement
• D) Ligules consisting of a fringe of hairs
Answer: B
Rationale: Sedges are characterized by "sedges have edges," meaning their stems
are distinctly triangular in cross-section. This distinguishes them from grasses,
which have round or flattened stems, and broadleaves, which have square or
round stems.
2. A "winter annual" weed is best described as a plant that:
• A) Germinates in the spring and dies in the winter
• B) Germinates in the fall, overwinters as a rosette, and seeds in the spring
• C) Lives for three or more years
• D) Only grows in high-altitude environments
Answer: B
Rationale: Winter annuals, such as Common Chickweed and Shepherd's Purse,
,germinate when temperatures drop in the fall, grow slowly through the winter as
a low rosette, and complete their life cycle (flowering and seeding) by late spring
or early summer before dying.
3. Which structure allows Johnsongrass (Sorghum halepense) to spread
vegetatively and persist as a perennial?
• A) Bulbs
• B) Stolons
• C) Rhizomes
• D) Taproots
Answer: C
Rationale: Johnsongrass is a highly invasive perennial weed that spreads via
aggressive underground stems called rhizomes. This makes it difficult to control
because the plant can regrow even if the above-ground portion is destroyed by fire
or mowing.
4. Barnyardgrass can be distinguished from other summer annual grasses by its
lack of:
• A) A root system
• B) Seeds
• C) A ligule and auricles
• D) Chlorophyll
Answer: C
Rationale: Barnyardgrass (Echinochloa crus-galli) is one of the few common grass
weeds that lacks both a ligule and auricles at the leaf collar. This characteristic is a
key identifying feature that separates it from foxtails and crabgrasses.
,5. The term "ephemeral weed" refers to a plant that:
• A) Lives for exactly one year
• B) Completes multiple generations in a single growing season
• C) Lives for 100 years
• D) Only grows in aquatic environments
Answer: B
Rationale: Ephemeral weeds, such as Annual Bluegrass (Poa annua), can complete
their entire life cycle in just a few weeks and produce multiple generations within
one growing season, making them difficult to control.
6. A biennial weed completes its life cycle in:
• A) One year
• B) Two years
• C) Three years
• D) Four or more years
Answer: B
Rationale: Biennials, like Common Mullein and Wild Carrot, require two years. The
first year is vegetative growth (a rosette), and the second year they bolt, flower,
produce seed, and die.
7. The cotyledon (seed leaf) shape of a broadleaf weed seedling is important for
identification because:
• A) It determines the herbicide to use
• B) It helps distinguish between species at the early growth stage
, • C) It affects the soil pH
• D) It indicates the weed's native origin
Answer: B
Rationale: Cotyledon shape, size, and color are often the first visible characteristics
of a seedling and can be used to identify weed species before true leaves develop,
which is critical for early post-emergence herbicide decisions.
8. Which of the following is a characteristic of a monocot weed?
• A) Net-veined leaves
• B) Fibrous root system
• C) Two cotyledons
• D) Branching taproot
Answer: B
Rationale: Monocots (grasses, sedges, and lilies) have fibrous root systems,
parallel-veined leaves, and one cotyledon. Broadleaf weeds (dicots) have net-
veined leaves, taproots, and two cotyledons.
9. The leaf collar of a grass plant is the:
• A) Tip of the leaf blade
• B) Junction where the leaf blade meets the sheath
• C) Root system
• D) Flower head
Answer: B
Rationale: The leaf collar is the region on the outside of the leaf where the blade
joins the sheath. It is a key identification feature because it may have a ligule,
auricles, or neither.
