International Society of
YR A S S O L G · A S I
Arboriculture
✦ ✦
ISA Certified Arborist Program
EST. 1924
P R O M O T I N G T H E P R O F E S S I O N A L P R A C T I C E O F A R B O R I C U LT U R E
ISA Certified Arborist — Comprehensive Glossary
A R B O R I CU LT U RA L T E R M I N O LO G Y O –S — CO M P L E T E ST U DY G U I D E
INSTITUTION International Society of PROGRAM ISA Certified Arborist Certification
Arboriculture (ISA)
COURSE CODE ISA — Glossary Study Set COURSE TITLE Arboriculture — Comprehensive
Terminology
ACADEMIC YEAR EXAM TITLE ISA Certified Arborist —
Comprehensive Glossary
TOTAL QUESTIONS 155 Questions FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question unless otherwise instructed.
▸ Tree biology, pruning practices, soil science, pest management, and structural support systems are all
testable content.
▸ Correct answers and detailed rationales appear below each question for study purposes.
▸ All content is derived from ISA Certified Arborist study materials.
, SECTION I — ARBORICULTURAL TERMINOLOGY: O
Questions 1 – 155
THROUGH S
1. What is the term for the sound of wind in the trees and rustling of leaves?
A. Phenology
B. Psithurism
C. Paraheliotropism
D. Phototropism
CORRECT ANSWER B — Psithurism
RATIONALE Psithurism is the specific term for the sound of wind moving through trees and
rustling leaves. Phenology (A) is the timing of natural processes. Paraheliotropism
(C) is leaf movement to avoid sun. Phototropism (D) is growth stimulated by light.
2. What is the term for the removal of nitrates, phosphates, and other contaminants from soil
and water by trees?
A. Phytotechnology
B. Phytoremediation
C. Phytonicides
D. Pneumatic soil excavation
CORRECT ANSWER B — Phytoremediation
RATIONALE Phytoremediation is the use of trees and plants to remove contaminants
including nitrates and phosphates from soil and water. Phytotechnology (A) is the
broader field including constructed wetlands. Phytonicides (C) are defensive
essential oils released by trees. Pneumatic soil excavation (D) uses pressurized air
to remove soil.
,3. What does the term "shall" denote in arboricultural standards and specifications?
A. An advisory recommendation
B. A mandatory requirement
C. An optional guideline
D. A suggested best practice
CORRECT ANSWER B — A mandatory requirement
RATIONALE In arboricultural standards and specifications, "shall" denotes a mandatory
requirement that must be followed. "Should" (A) denotes an advisory
recommendation. These distinctions are critical in contract specifications and
safety standards.
4. What is the function of parenchyma cells in trees?
A. Transporting water upward through the tree
B. Thin-walled cells that contain living substances and store energy reserves
C. Forming the outer protective bark layer
D. Conducting carbohydrates downward
CORRECT ANSWER B — Thin-walled cells that contain living substances and store energy
reserves
RATIONALE Parenchyma cells are thin-walled living cells that store energy reserves (starch)
and are part of the symplast network. Xylem tracheids and vessels (A) transport
water. Outer bark (C) is composed of dead cells. Phloem (D) conducts
carbohydrates.
, 5. What is the primary root in a seed that emerges first during germination called?
A. Radicle
B. Taproot
C. Pioneer root
D. Prop root
CORRECT ANSWER A — Radicle
RATIONALE The radicle is the embryonic root in a seed and is the first structure to emerge
during germination. It develops into the primary root system. Taproots (B) grow
downward from the radicle. Pioneer roots (C) are destined to become woody
roots. Prop roots (D) grow downward from branches.
6. What is a root that encircles all or a portion of a trunk and impedes development and
circulation called?
A. Prop root
B. Girdling root
C. Pioneer root
D. Striker root
CORRECT ANSWER B — Girdling root
RATIONALE A girdling root encircles or contacts the trunk or a buttress root, impeding
vascular flow and compromising tree health and stability. These should be
removed. Prop roots (A) grow downward from branches. Pioneer roots (C)
become woody roots. Striker roots (D) grow vertically downward.
YR A S S O L G · A S I
Arboriculture
✦ ✦
ISA Certified Arborist Program
EST. 1924
P R O M O T I N G T H E P R O F E S S I O N A L P R A C T I C E O F A R B O R I C U LT U R E
ISA Certified Arborist — Comprehensive Glossary
A R B O R I CU LT U RA L T E R M I N O LO G Y O –S — CO M P L E T E ST U DY G U I D E
INSTITUTION International Society of PROGRAM ISA Certified Arborist Certification
Arboriculture (ISA)
COURSE CODE ISA — Glossary Study Set COURSE TITLE Arboriculture — Comprehensive
Terminology
ACADEMIC YEAR EXAM TITLE ISA Certified Arborist —
Comprehensive Glossary
TOTAL QUESTIONS 155 Questions FORMAT Multiple Choice — Select the
Single Best Answer
EXAMINATION INSTRUCTIONS
▸ Select the single best answer for each question unless otherwise instructed.
▸ Tree biology, pruning practices, soil science, pest management, and structural support systems are all
testable content.
▸ Correct answers and detailed rationales appear below each question for study purposes.
▸ All content is derived from ISA Certified Arborist study materials.
, SECTION I — ARBORICULTURAL TERMINOLOGY: O
Questions 1 – 155
THROUGH S
1. What is the term for the sound of wind in the trees and rustling of leaves?
A. Phenology
B. Psithurism
C. Paraheliotropism
D. Phototropism
CORRECT ANSWER B — Psithurism
RATIONALE Psithurism is the specific term for the sound of wind moving through trees and
rustling leaves. Phenology (A) is the timing of natural processes. Paraheliotropism
(C) is leaf movement to avoid sun. Phototropism (D) is growth stimulated by light.
2. What is the term for the removal of nitrates, phosphates, and other contaminants from soil
and water by trees?
A. Phytotechnology
B. Phytoremediation
C. Phytonicides
D. Pneumatic soil excavation
CORRECT ANSWER B — Phytoremediation
RATIONALE Phytoremediation is the use of trees and plants to remove contaminants
including nitrates and phosphates from soil and water. Phytotechnology (A) is the
broader field including constructed wetlands. Phytonicides (C) are defensive
essential oils released by trees. Pneumatic soil excavation (D) uses pressurized air
to remove soil.
,3. What does the term "shall" denote in arboricultural standards and specifications?
A. An advisory recommendation
B. A mandatory requirement
C. An optional guideline
D. A suggested best practice
CORRECT ANSWER B — A mandatory requirement
RATIONALE In arboricultural standards and specifications, "shall" denotes a mandatory
requirement that must be followed. "Should" (A) denotes an advisory
recommendation. These distinctions are critical in contract specifications and
safety standards.
4. What is the function of parenchyma cells in trees?
A. Transporting water upward through the tree
B. Thin-walled cells that contain living substances and store energy reserves
C. Forming the outer protective bark layer
D. Conducting carbohydrates downward
CORRECT ANSWER B — Thin-walled cells that contain living substances and store energy
reserves
RATIONALE Parenchyma cells are thin-walled living cells that store energy reserves (starch)
and are part of the symplast network. Xylem tracheids and vessels (A) transport
water. Outer bark (C) is composed of dead cells. Phloem (D) conducts
carbohydrates.
, 5. What is the primary root in a seed that emerges first during germination called?
A. Radicle
B. Taproot
C. Pioneer root
D. Prop root
CORRECT ANSWER A — Radicle
RATIONALE The radicle is the embryonic root in a seed and is the first structure to emerge
during germination. It develops into the primary root system. Taproots (B) grow
downward from the radicle. Pioneer roots (C) are destined to become woody
roots. Prop roots (D) grow downward from branches.
6. What is a root that encircles all or a portion of a trunk and impedes development and
circulation called?
A. Prop root
B. Girdling root
C. Pioneer root
D. Striker root
CORRECT ANSWER B — Girdling root
RATIONALE A girdling root encircles or contacts the trunk or a buttress root, impeding
vascular flow and compromising tree health and stability. These should be
removed. Prop roots (A) grow downward from branches. Pioneer roots (C)
become woody roots. Striker roots (D) grow vertically downward.
