Botany Basics
The science of plants — how they are built, how they function, how they grow
Chapter 10: Plant Classification — Families, Genera, Species
Why this matters: Classification is the language of botany. When you know a plant's family, you immediately know dozens of things about it — its likely chemistry, pollination method, edibility patterns, growth habit, and what its relatives look like. Knowing plant families is the single most powerful shortcut in plant identification, medicinal plant work, and understanding plant ecology.
10.1 Why Classification Matters
Without classification
From: 10.1 Why Classification Matters
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig01.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig01.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig01.png" alt="Without classification"></figure>
10.2 The Taxonomic Hierarchy
TAXONOMIC RANKS (broad to narrow)
From: 10.2 The Taxonomic Hierarchy
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig02.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig02.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig02.png" alt="TAXONOMIC RANKS (broad to narrow)"></figure>
10.3 Scientific Names — Why They Matter
BINOMIAL NOMENCLATURE (two-name system)
From: 10.3 Scientific Names — Why They Matter
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig03.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig03.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig03.png" alt="BINOMIAL NOMENCLATURE (two-name system)"></figure>
10.4 Major Plant Groups
PLANT KINGDOM overview
From: 10.4 Major Plant Groups
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig04.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig04.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig04.png" alt="PLANT KINGDOM overview"></figure>
10.5 Key Plant Families for Texas
Learning these 15 families covers the vast majority of plants you will encounter in Texas landscapes, gardens, and wild areas.
Asteraceae — The Daisy/Sunflower Family
ASTERACEAE (Compositae)
From: 10.5 Key Plant Families for Texas
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig05.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig05.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig05.png" alt="ASTERACEAE (Compositae)"></figure>
Fabaceae — The Legume/Bean Family
FABACEAE (Leguminosae)
From: 10.5 Key Plant Families for Texas
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig06.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig06.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig06.png" alt="FABACEAE (Leguminosae)"></figure>
Poaceae — The Grass Family
POACEAE (Gramineae)
From: 10.5 Key Plant Families for Texas
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig07.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig07.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig07.png" alt="POACEAE (Gramineae)"></figure>
Lamiaceae — The Mint Family
LAMIACEAE (Labiatae)
From: 10.5 Key Plant Families for Texas
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig08.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig08.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig08.png" alt="LAMIACEAE (Labiatae)"></figure>
Rosaceae — The Rose Family
ROSACEAE
From: 10.5 Key Plant Families for Texas
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig09.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig09.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig09.png" alt="ROSACEAE"></figure>
Apiaceae — The Carrot Family
APIACEAE (Umbelliferae)
From: 10.5 Key Plant Families for Texas
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig10.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig10.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig10.png" alt="APIACEAE (Umbelliferae)"></figure>
Solanaceae — The Nightshade Family
SOLANACEAE
From: 10.5 Key Plant Families for Texas
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig11.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig11.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig11.png" alt="SOLANACEAE"></figure>
Cucurbitaceae — The Gourd Family
CUCURBITACEAE
From: 10.5 Key Plant Families for Texas
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig12.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig12.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig12.png" alt="CUCURBITACEAE"></figure>
Additional Key Families — Quick Reference
BRASSICACEAE (Mustard family):
4 petals in cross shape: ✚
6 stamens (4 long, 2 short)
Silique or silicle fruit (pods)
Edible: cabbage, kale, broccoli, cauliflower,
Brussels sprouts, turnip, radish, arugula,
mustard greens, horseradish, watercress
All are the SAME species or close relatives
Flavor: spicy/sharp (glucosinolates)
Texas natives: peppergrass (Lepidium), rock cress
EUPHORBIACEAE (Spurge family):
MILKY LATEX when broken — key ID feature
Highly variable flower structure
Toxic in many (irritating skin/eyes)
Texas: poinsettia (native Mexico), snow-on-the-mountain,
tallow tree (invasive!), rubber tree
Castor bean (HIGHLY TOXIC — ricin source)
CONVOLVULACEAE (Morning glory family):
Twining vines
Funnel-shaped flowers
Often 5-lobed
Texas: morning glory (ornamental/edible seeds for birds)
Sweet potato (Ipomoea batatas) — edible
Bindweed (Convolvulus) — invasive weed
LILIACEAE / related families (Lily-like monocots):
6 tepals (petals + sepals similar)
3+3 or 6 arrangement
Often bulbs or rhizomes
Texas: wild onion (Allium, now Amaryllidaceae),
rain lily (Zephyranthes), spider lily,
Texas star (Lindheimera texana)
CAUTION: Allium (onion/garlic) — edible, pungent smell
Death camas (Zigadenus) — TOXIC, similar looking
Identification by smell: onion smell = Allium safe
No onion smell with bulb = suspect toxicity
CACTACEAE (Cactus family):
Succulent stems
Spines from areoles (modified buds)
Often CAM photosynthesis
Texas: prickly pear (Opuntia — edible pads and fruit),
cholla, barrel cactus, claret cup,
horse crippler, star cactus10.6 Using Classification in the Field
IDENTIFICATION WORKFLOW:
Step 1: Is it a monocot or dicot?
Monocot: parallel veins, parts in 3s
Dicot: netted veins, parts in 4s or 5s
Step 2: What family?
Look for DIAGNOSTIC FEATURES:
Square stem + opposite + aromatic = Lamiaceae
Compound umbel = Apiaceae (be careful!)
5 petals + many stamens + rose smell = Rosaceae
Butterfly flower + pod = Fabaceae
Daisy head = Asteraceae
4 petals in cross + pungent = Brassicaceae
Milky latex = probably Euphorbiaceae
Step 3: What genus?
Within the family, note:
Leaf shape and arrangement
Flower color and structure
Fruit type
Stem characteristics
Habitat
Step 4: What species?
Most detailed features
Use a regional field guide
Photograph multiple parts
Smell (carefully)
Check multiple sources before using
NEVER consume a plant unless you have
made a POSITIVE identification from
multiple reliable sourcesChapter Summary
HIERARCHY: Domain → Kingdom → Phylum → Class →
From: Chapter Summary
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig13.png
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1. The species is the broadest level of the taxonomic hierarchy.
2. A genus contains one or more species that share common ancestry.
3. Binomial nomenclature uses genus and species name together.
4. Scientific names are always written in English.
5. Angiosperms are flowering plants that produce seeds enclosed in fruit.
6. Gymnosperms produce seeds in cones or exposed on scales.
7. Ferns are angiosperms.
8. Monocots typically have flower parts in multiples of three.
9. Dicots typically have flower parts in multiples of four or five.
10. Grasses are monocots.
11. The Fabaceae (legume) family is characterized by explosive pods and nitrogen fixation.
12. Members of the Asteraceae family have composite flower heads.
13. The Lamiaceae (mint) family has square stems and opposite leaves.
14. The Solanaceae family includes tomatoes, peppers, potatoes, and deadly nightshade.
15. Phylogenetic classification is based on evolutionary relationships.
16. Common names are more reliable than scientific names for plant identification.
17. Variety, cultivar, and subspecies all describe variation below the species level.
18. The Rosaceae family includes roses, apples, pears, cherries, and strawberries.
19. Bryophytes (mosses and liverworts) have a well-developed vascular system.
20. Understanding plant families helps predict edibility, toxicity, and uses.
1. List the levels of the taxonomic hierarchy from broadest to most specific.
2. Why are scientific names more reliable than common names?
3. What is the difference between angiosperms and gymnosperms?
4. What are the key differences between monocots and dicots?
5. Describe three characteristics of the Fabaceae (legume) family.
6. What characteristics distinguish the Asteraceae family?
7. Why is knowing a plant's family useful for the land steward?
8. Describe two characteristics of the Lamiaceae (mint) family.
9. What is a cultivar and how does it differ from a variety?
10. Name five important Texas plant families and one key species from each.
1. The two-part scientific name system using genus and species is called nomenclature.
2. The broadest level of the taxonomic hierarchy is .
3. Flowering plants that produce seeds enclosed in fruit are called .
4. Plants with one cotyledon, parallel venation, and flower parts in 3s are .
5. Plants with two cotyledons, net venation, and flower parts in 4s or 5s are .
6. The family that includes beans, peas, mesquite, and clover is .
7. The family with composite flower heads including sunflowers and daisies is .
8. The family with square stems, opposite leaves, and aromatic properties is .
9. The family including tomatoes, peppers, potatoes, and deadly nightshade is .
Complete in the field. Check each off as you go.
1. Family Identification Walk: Walk your property and identify plants from at least 5 different families. Use a field guide. Record: family, common name, scientific name, and one identifying feature.
2. Legume Scouting: Find all Fabaceae members on your property. Identify: root nodules (dig carefully), pod shape, leaflet arrangement. Note which are native vs introduced.
3. Asteraceae Survey: Find 5 different Asteraceae plants. Examine the composite head with a magnifying glass — distinguish ray flowers (outer, strap-like) from disc flowers (inner, tubular).
4. Monocot vs Dicot Sort: Collect 10 plants. Sort into monocot vs dicot based on: venation, flower part count, stem cross-section (scattered vs ring vascular bundles). Verify with a field guide.
5. Scientific Name Practice: Choose 10 plants on your property and look up their full scientific names. Practice writing and pronouncing them. Note where the genus name might indicate a characteristic of the plant.
Practice Exercises
- You find a plant with square stems, opposite leaves, and it smells like oregano when crushed. What family is it almost certainly in?
- Why is it dangerous to eat any white-flowered plant with compound umbels unless you are completely certain of its identity?
- What do tomatoes, potatoes, peppers, and tobacco have in common beyond both being plants?
- You find a plant with milky white sap oozing from a broken stem. What family is this likely from and what does this tell you about handling it?
- Why do all squash, cucumbers, and melons need bees to produce fruit, and what can you do if bees are scarce?
- A seed packet says "Lupinus texensis." Break this name down and explain what each part tells you.
Curriculum 01 Complete — Botany Basics
You have now covered:
✓ Ch 01: The Plant Cell
✓ Ch 02: Plant Tissues
✓ Ch 03: Roots
✓ Ch 04: Stems
✓ Ch 05: Leaves
✓ Ch 06: Flowers
✓ Ch 07: Seeds and Fruit
✓ Ch 08: Photosynthesis and Respiration
✓ Ch 09: Plant Hormones and Growth Responses
✓ Ch 10: Plant Classification
Next: Curriculum 02 — Plant Taxonomy and Field Identification
(Building on this foundation to identify plants in the field)Connections to Other Topics
→ C02 Plant Taxonomy: Complete curriculum on identification and naming
From: Connections to Other Topics
Image file: ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig14.png
Save image as ../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig14.png in this folder, then replace this block with:<figure><img src="../../../images/s01-foundation/c01-botany-basics/ch10/c01-botany-basics_ch10_plant_classification_fig14.png" alt="→ C02 Plant Taxonomy: Complete curriculum on identification and naming"></figure>
Curriculum 01: Botany Basics Complete