Lecture 04

Monocotyledoneae

General features of Monocotyledons

1. Plants more commonly herbaceous and rarely woody.

2. Embryo with typically one cotyledon.

3. Stems with closed vascular bundles which scattered throughout but not arranged in a single cylinder.

4. Leaves usually paralled-veined with almost entire margins.

5. Flowers usually with parts in 3's or multiple of 3 (trimerous).

The following a key by which orders may be classified:

A. Perianth wanting or reduced to bristles, bracts, scales.

B. Flowers not in axils of dry chaffy bracts.

C. Perianth represented by bristles or scales, leaves

stiffly long and sword-shape.............................................................. Pandanales.

CC. Perianth usually of fleshy or herbaceous bracts,

Leaves various or wanting fruit usually drupaceous or baccate.

D. Seeds without endosperm, pollen grains in

trials, fruit one seeded......................................................................Heloboiae.

DD. Seeds with endosperm, pollen grains in diads

or tetrads, fruit more than one seeded..................................Spathiflorae.

BB. Flowers in axils of dry, chaffy bracts (Glume)............................................Glumiflorae.

AA. Perianth generally present and in two series, the inner or both

usually more or less petaloid.

E. Plant typically woody, leaves generally compound or

palmately lobed, cleft or divided.

F. Carpels 3 in each ovary each cell one ovuled..............................................Principes.

EE. Plant herbaceous or if woody the leaves never compound

G. Seeds not minute, endosperm present.

H. Endosperm mealy ............................................................................Farinosae.

HH. Endosperm fleshy, horny or cartilaginous.

I. Functional  stamens 3-6 seeds rarely arillate...........................Liliflorae.

II. Functional stamen one, seeds mostly arillate....................Scitamineae.

GG. Seeds very minute, lacking endosperm..............................................Microspermae.

Selected Orders & Families of the Monocotvledonous Plants

Order: Pandanales

Plants dioecious or monoecious, leves linear, flowers unisexual, perianthbristles or dry scales, stamens 1-many, ovary 1-many carpels, fruits nut-like, seeds endospermic, pollen in diads, example family Typhaceae.

Order: Heloboiae

Aquatic habitat, flowers cyclic, uni- or bisexual, regular, naked or with simple or double perianth, stamens 1-many, ovary 1-many free carpels, superior or inferior, seeds exendospermic, example family Potamogetonaceae.

Order: Spathiflorae

Herbs or climbers, flowers minute on thickened spadix, perianth absent or reduced, ovary superior, fruit berry, example family Araceae.

Order: Glumiflorae

Annual or perennial herbs, sometimes shrubs or trees. Stems cylindencal or triangular with or without elongated intermodes. Usually the plants grow in tufts. Leaves linear, entire with parallel venation and sheathing base often with a memberanous outgrowth called ligule between the sheathing base and blade represinting the petiole. Flowers in inflorescence called spike, small, naked or with a perianth represented by scales or hair-like structure enclosed in scale-like bracts called glume. Stamens three in one whole Gynoeciium with 1-3 styles. Fruit caryopsis.

Key to Families of Order Glumiflorae

   A. Stem Terete, hollow, Stamens versatile, Stigma Feathery, presence of

Lodicule, lemma and palea with or without awn ………………………………..Gramineae

AA. Stem triangular, Solid………………………...……………………………………Cyperaceae

Family: Gramineae

Vegetative characters:

1. Root system: adventitious.
2. Stem: culm-like.
3. Leaves: linear leaves with parallel venation, opened sheathing base, ligule,2 auricles.

Floral characters:

1. Spike inflorescence.
2. Trimerous florets.
3. Perianth: may be present or absent, if present it is represented by 2 lodicules.
4. Androecium: 3 stamens, versatile anthers.
5. Gynoecium: superior ovary, 1 carpel, 1 locule, basal placentation, 2 feathery stigma.

Family: Cyperaceae

Vegetative characters:

1. Root system: adventitious.
2. Stem: Angeled.
3. Leaves: Linear with parallel venation, closed sheathing base.

Floral characters:

4. Spike inflorescence.
5. Trimerous florets.
6. Perianth: absent.
7. Androecium: 3 stamens, versatile anthers.
8. Gynoecium: Superior ovary, 3 carpels, 1 locule, basal placentation, 3- feathery stigma.

Order: Principes

Plants tree-like or sometimes shrubs. Root system adventitious, stem woody with prinnately or palmately compound leaves. Inflorescence mostly a compound spadix. Flowers; pedicellate or sessile, bracteate unisexual or hermaphrodite, actionomorphic, hypogenous. Perianth six in two whorls. Stamens six in two whorls. Carpels three, apocarpous ovary trilocular with axile placentation. In Phoenix (Family Palmae) only the anterior locule is fertile. Fruit, berry.

Family: Palmae

Vegetative characters:

1. Root system: adventitious fiberous.
2. Stem: Unbranched.
3. Gross morphology: tiller.
4. Leaves: Crown-like with parallel venation.

Floral characters:

5. Spadix inflorescence.
6. Trimerous unisexual flower.
7. Perianth: undifferentiated into calyx nor corolla.
8. Androecium: 6 stamens.
9. Gynoecium: superior ovary, 3 carpels, apocarpous, basal placentation.

Order: Farinosae

Ovary superior, seeds with mealy endosperm, example family Commelinaceae.

Family Commelinaceae

Vegetative characters:

1. Leaves:  with parallel venation, ochreate stipules.
2. Root system: adventitious.

Floral characters:

3. Trimerous flower.
4. Perianth: differentiated into calyx and corolla.
5. Androecium: 6 stamens.
6. Gynoecium: Superior ovary, 3 carpels, 3 locules, axile placentation.

Order: Liliflorae

Plants generally herbs which are perennial by means of abulb or rihizome. Flowers bisexual usually regular or sometimes Zygomorphic. Perianth petaliod or glumaceous. Ovary superior or inferior, trilocular. Fruit capsule or berry.

Key to Families of Order Liliflorae

    A. Flowers glumaceous ……………………………………………………………..…..Juncaceae

AA. Flowers not glumaceous

  B. Flowers Hypogenous, Ovary Superior…………………………………….……Liliaceae

BB. Flowers Epigynous, Ovary inferior

   C. Stamens 3+0…………………………………………………………...Iridiaceae

CC. Stamens 3+3, Corona sometimes present………………...……..Amaryllidaceae

Family: Liliaceae

Vegetative characters:

1. Leaves: succulent with parallel venation.
2. Root system: adventitious.

Floral characters:

3. Trimerous flower.
4. Perianth: undifferentiated into calyx nor corolla.
5. Androecium: 6 stamens, introse anthers.
6. Gynoecium: Superior ovary, 3 carpels, 3 locules, axile placentation.

Family: Iridaceae

Vegetative characters:

1. Leaves: Equitant with parallel venation.
2. Stem: Subterranean stem (bulb, rhizome, corm).
3. Root system: adventitious.

Floral characters:

4. Trimerous flower.
5. Two bracts present.
6. Perianth: undifferentiated into calyx nor corolla.
7. Androecium: 3 epitepalous stamens, extrose anthers.
8. Gynoecium: Inferior ovary, 3 carpels, 3 locules, axile placentation.

Family: Amaryllidaceae

Vegetative characters:

1. Leaves: radical with parallel venation.
2. Stem: subterranean stem (bulb or rhizome).
3. Root system: adventitious fiberous.

Floral characters:

4. Trimerous flower.
5. Perianth: undifferentiated into calyx nor corolla.
6. Androecium: 6 epitepalous stamens, introse anthers
7. Gynoecium: Inferior ovary, 3 carpels, 3 locules, axile placentation.

Order: Scitaminae

Flower usually Zygomorphic, the functional stamens one or rarely four. Ovary inferior. Leaves with open sheathing base (rarely closed), seeds endospermic.

Key to Families of Order Scitaminae

 A. Functional stamens: 5+1 staminodes………………………………………………….Musaceae

AA. Functional stamens: stamen + petaloid stmens………………………………..……..Cannaceae

Family: Musaceae

Vegetative characters:

1. Leaves: with parallel coastal venation.
2. Stem: subterranean (rhizome), pseudo-aerial stem.
3. Root system: adventitious.

Floral characters:

4. Spadix inflorescence.
5. Trimerous flower.
6. Perianth: undifferentiated into calyx nor corolla.
7. Androecium: 5 fertile stamens.
8. Gynoecium: Inferior ovary, 3 carpels, 3 locules, axile placentation.

Family: Cannaceae

Vegetative characters:

1. Leaves: with parallel venation.
2. Root system: adventitious.

Floral characters:

3. Trimerous flower.
4. Perianth: differentiated into calyx and corolla.
5. Androecium: 6 stamens, only 1 anther lobe  fertile, the others metamorphosed into petals.
6. Gynoecium: Inferior ovary, 3 carpels, 3 locules, axile placentation, petaloid style.

Order: Microspermae

Flower zygomorphic, bisexual, ovary inferior and tricarpellate, stamens adherent or adnateto style, seeds minute and exendospermic, example family Orchidaceae.