Dichotomous Key Practice Worksheets | PDF - Free Printable

Let's solve this dichotomous key practice problem step by step. We are given five leaf diagrams labeled A through E and a dichotomous key to identify them.

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Step-by-step Analysis

We will use the key to determine the identity of each leaf based on its shape, edge, and vein pattern.

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🔍 Leaf A

- Shape: Oval-shaped (not star-shaped) → Go to Step 2
- In Step 2:
- Is it shorter and wide? → Yes, looks broad and oval
- So go to Step 4
- Step 4:
- Does it have 4 veins on each side? → Let’s count: It has 5 veins on each side → No
- Does it have 5 veins on each side? → Yes
✔ Answer: Beech

> A = Beech

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🔍 Leaf B

- Shape: Oval-shaped → Go to Step 2
- Step 2:
- Is it shorter and wide? → Yes
- Go to Step 4
- Step 4:
- Count veins: Looks like 4 veins on each side
✔ Answer: Birch

> B = Birch

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🔍 Leaf C

- Shape: Star-shaped (has multiple lobes like a star) → Go to Step 3
- Step 3:
- Edge: Jagged edges → Yes
✔ Answer: Sugar Maple

> C = Sugar Maple

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🔍 Leaf D

- Shape: Oval-shaped → Go to Step 2
- Step 2:
- Longer and narrow → Yes (longer than wide)
✔ Answer: Hickory

> D = Hickory

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🔍 Leaf E

- Shape: Star-shaped → Go to Step 3
- Step 3:
- Edge: Jagged edges → Yes
✔ Answer: Sugar Maple

Wait! But we already have C as Sugar Maple. Can two leaves be the same?

Yes — different species can have similar shapes, and in this case, both C and E are star-shaped with jagged edges, so both should be Sugar Maple.

But let’s double-check:

- C: Has 5 lobes, jagged edges → Classic Sugar Maple
- E: Also has 5 lobes, jagged edges → Also Sugar Maple

✔ Both C and E match Sugar Maple

But wait — the key only gives one option for jagged star-shaped leaves: Sugar Maple

So both C and E are Sugar Maple

But the question asks to label each leaf individually.

So unless there's an error, both are Sugar Maple

However, look again at C and E:

- C is more rounded, lobed, but not deeply cut
- E has deeper, sharper lobes

But according to the key, only "jagged edges" determines Sugar Maple.

And both have jagged edges.

So both C and E → Sugar Maple

But that might be acceptable if the key doesn't distinguish further.

Wait — perhaps E is meant to be different?

Let’s recheck E:

- E is clearly star-shaped (like maple), jagged edges → matches Sugar Maple
- C also has jagged edges and star shape → same

But maybe C is actually Hickory?

No — Hickory is in Step 2B: longer and narrow → C is not long and narrow, it's wide and lobed

So C must go to Step 1B → star-shaped → Step 3 → jagged → Sugar Maple

Same for E

So both C and E are Sugar Maple

But the key doesn’t differentiate between them.

So we must accept that.

Wait — but C has 5 main lobes, and E also has 5 — yes.

So both are Sugar Maple.

But let’s check A, B, D again:

- A: oval, short/wide, 5 veins → Beech ✔
- B: oval, short/wide, 4 veins → Birch ✔
- D: oval, longer/narrow → Hickory ✔
- C: star-shaped, jagged → Sugar Maple ✔
- E: star-shaped, jagged → Sugar Maple ✔

So C and E both identified as Sugar Maple

But that’s fine — the key allows for multiple leaves of the same type.

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✔ Final Answers:

A) Beech
B) Birch
C) Sugar Maple
D) Hickory
E) Sugar Maple

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📝 Summary of Reasoning:

| Leaf | Shape | Edges | Veins/Size | Key Path | ID |
|------|-------------|-----------|--------------------|-----------------------------------------------|---------------|
| A | Oval | Smooth? | 5 veins per side | 1A → 2A → 4B | Beech |
| B | Oval | Smooth? | 4 veins per side | 1A → 2A → 4A | Birch |
| C | Star-shaped | Jagged | N/A | 1B → 3B | Sugar Maple |
| D | Oval | Smooth? | Long & narrow | 1A → 2B | Hickory |
| E | Star-shaped | Jagged | N/A | 1B → 3B | Sugar Maple |

> Note: The key does not distinguish between different types of star-shaped leaves beyond edge type, so both C and E are Sugar Maple.

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✔ Final Answer:

A) Beech
B) Birch
C) Sugar Maple
D) Hickory
E) Sugar Maple

Let me know if you'd like a visual explanation or diagram-based reasoning!