Page 128 - Ultimate Visual Dictionary (DK)

PLANTS

Monocotyledons COMPARISONS BETWEEN
MONOCOTYLEDONS AND
DICOTYLEDONS
and dicotyledons Vein Leaflet
(parallel
venation)

FLOWERING PLANTS (PHYLUM ANGIOSPERMOPHYTA) are divided into two classes:
monocotyledons (class Monocotyledoneae) and dicotyledons (class
Dicotyledoneae). Typically, monocotyledons have seeds with
one cotyledon (seed leaf); their foliage leaves are narrow with Petiole
parallel veins; the flower components occur in multiples of (leaf stalk)
three; sepals and petals are indistinguishable and are known
as tepals; vascular (transport) tissues are scattered in random
CROSS-SECTION bundles throughout the stem; and, since they lack stem Emerging
THROUGH leaf
MONOCOTYLEDONOUS cambium (actively dividing cells that produce wood),
LEAF BASES most monocotyledons are herbaceous (see pp. 128-129).
Dicotyledons have seeds with two cotyledons; leaves are broad with a central
midrib and branched veins; flower parts occur in multiples of four or five;
sepals are generally small and green; petals are large and colorful; vascular Leaf base
bundles are arranged in a ring around the edge of the stem; and, because many
dicotyledons possess wood-producing stem cambium, there are woody forms
(see pp. 130-131) as well as herbaceous ones. Adventitious
root
Xylem
Vascular tissue
Water-absorbing A MONOCOTYLEDON
parenchyma Mesophyll Phloem Palisade mesophyll Paradise palm
(photosynthetic (tightly packed
(packing (Howea forsteriana)
tissue) tissue) photosynthetic tissue)
Vein Collenchyma
Spongy
mesophyll (supporting
(loosely packed tissue)
Sunken Vein
stoma photosynthetic
tissue) Vascular Xylem
(pore) tissue Epidermis
Epidermis Phloem (outer layer
Cuticle (outer layer of cells) of cells)
(waterproof Sclerenchyma Parenchyma
covering) (strengthening tissue) (packing tissue)
Midrib
MICROGRAPH OF CROSS-SECTION THROUGH MICROGRAPH OF CROSS-SECTION THROUGH
A MONOCOTYLEDONOUS LEAF A DICOTYLEDONOUS LEAF
Yucca (Yucca sp.) Crab apple (Malus sp.)
Lateral, inner tepal
Outer tepal (monocotyledonous
(monocotyledonous petal) Filament Stigma
sepal) Stamen
Anther
Pollen on
anther
Column
(stamens
and style)

Funnel guide for Petal
bird pollinators’ beak
Guide hair
Labellum (lip)
A MONOCOTYLEDONOUS FLOWER forming landing stage A DICOTYLEDONOUS FLOWER
Orchid for pollinator Hibiscus
(Phalaenopsis sp.) (Hibiscus rosa-sinensis)

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