2.1 Root System

Tap root system (dicots) vs fibrous root system (monocots). Modifications: storage (carrot, radish, turnip, sweet potato), supportive (prop — banyan; stilt — maize), and respiratory (pneumatophores — Rhizophora). Critical distinction: sweet potato is a root modification; potato is a stem modification — determined by presence/absence of buds.

2.2 Stem System

Identified by nodes, internodes, axillary buds, and ability to turn green in light. Underground: rhizome (ginger), tuber (potato), bulb (onion), corm (Colocasia). Subaerial: runner, stolon, offset, sucker. Aerial: tendril (Passiflora), thorn (Bougainvillea), phylloclade (Opuntia).

2.3 Leaf System

Reticulate venation = dicot; parallel venation = monocot. Phyllotaxy: alternate/opposite/whorled. Leaf modifications — tendril (pea), spine (cactus), pitcher (Nepenthes), bladder (Utricularia), phyllode (Acacia).

2.4 Inflorescence and Flowers

Racemose (indefinite — base to apex opening) vs cymose (definite — apex oldest). Aestivation: valvate, twisted, imbricate, vexillary. Placentation: marginal, axile, parietal, free central, basal — each with a diagnostic example.

2.5 Fruits and Seeds

Fruits: simple (drupe/mango, berry/tomato), aggregate (Polyalthia), composite (sorosis/pineapple, syconus/fig). Dicot seed (gram): testa + tegmen, two cotyledons, radicle/plumule/hypocotyl/epicotyl. Monocot seed (maize): scutellum (one cotyledon), prominent endosperm, coleoptile over plumule, coleorhiza over radicle, caryopsis (pericarp fused with testa).

2.6 Seven Plant Families

Each family has a unique fingerprint: Fabaceae (diadelphous 9+1, vexillary, marginal, legume), Solanaceae (5 epipetalous, axile, berry), Liliaceae (6 tepals, trimerous, axile, capsule), Malvaceae (epicalyx, monadelphous, axile), Brassicaceae (tetradynamous, parietal, siliqua), Asteraceae (capitulum, syngenesious, cypsela, pappus), Poaceae (lodicules, versatile anthers, caryopsis).

2.7 Plant Tissues

Meristematic: apical, lateral (cambium), intercalary. Simple permanent: parenchyma (living, cellulose), collenchyma (living, pectin corners), sclerenchyma (dead, lignin). Complex: xylem (vessels/tracheids — dead; xylem parenchyma — living), phloem (sieve tubes — living, enucleated; companion cells — living, nucleated).

2.8 Comparative Anatomy

Dicot root: 2–4 xylem, cambium present. Monocot root: polyarch, no cambium, large pith. Dicot stem: ring VBs, open (cambium), secondary growth possible. Monocot stem: scattered VBs, closed, no secondary growth. Dicot leaf: dorsiventral (palisade + spongy). Monocot leaf: isobilateral (uniform mesophyll, bulliform cells).