Lecture 05

Dicotyledoneae

General characteristic features

1. Embryo with typically 2 cotyledons.

2. Stem with arranged vascular bundles.

3. Leaves usually with netted venation of the palmate or pinnate type.

4. Flower basically with parts numerous or in multiples or of 4 or 5 (Tetramerous or pentamerous),

Key for the orders of Dicotyledoneae

A. Flowers without a sepaloid or petaloid Perianth (bracts may be present).

     B. Leaves in whorls 4-16 scale-like, branches striated; stamens single....................Verticillatae

     BB. Leaves otherwise; Stamens 2-more ..........................................................................Salicales

AA. Flowers with a Perianth of sepals or petals or both.

     C. Petals distinct or mostly so, usually when not so are fused with sepals and stamens to form an

hypanthiun.

          D. Perianth parts generally alike (sepaloid or petaloid) and undifferentiated into calyx and

                corolla.

                   E. Flowers mostly unisexual   ............................................................................Urticales

                 EE. Flowers mostly bisexual ............................................................................ Polygonals

       

          DD. Perianth differentiated into calyx and corolla (corolla sometimes absent).

                   F. Embryo coiled or curved, rarely   straight, placentation basal or

free-central .........................................................................................Centrospermae

                 FF. Embryo straight, placentation usually axile or parietal.

                          G. Floral parts spirally arranged, gynoecium mostly   multipistillate, each   

                                  pistil monocarpellate............................................................................. Ranales

                       GG. Floral parts cyclic, gynoecium  mostly unipistillate and each pistil

                                syncarpous (except some Resales).

                                H. Placentation basically parietal (no hypanthium) ..........................Rhoeadales

                             HH. Placentaion axile or ovules few or solitary in a unilocular

                                         ovary hypanthium often present.

                                         I. Overy predominantly inferior or surrounded by hypanthium.

                                                Pistil 1 to many, sometimes syncarpous. Stamens mostly

                                                epigynous or perigynous ..........................................................Rosales

                                         II. Ovary inferior or superior almost always syncarpous.

                                                   J. Stamens rarely more than twice as many as sepals in

                                                          one or two whorls, hypogynous.

                                                           K. The stamens twice as as sepals in two whorls or in

                                                                     1 whorl and opposite the sepals.

                                                                     L. Ovules pendulous with a ventral raphe and

                                                                              micropyle up or erect with a dorsal raphe and the

                                                                               micropyle down ....................................Geraniales

                                                                     LL. Ovules pendulous with a ventral raphe and

                                                                              micropyle down or erect with a ventral raphe

                                                                               and the micropyle up ............................Sapindales

                                                           KK. The  stamens as many as the sepals and

                                                                        alternating with them

                                                                         (opposite the petals)....................................Rhamnales

                                                

                                                       JJ. Stamens usually numerous.

                                                             M. Ovary superior

                                                                      N. Placentation usually axile. Sepals

                                                                                usually valvate.........................................Malvales

                                                                   NN. Placentation usually parietal, sepals usually

                                                                                  imbricate .............................................Parietales

                                                         MM. Ovary usually inferior or surrounded by an hypanthium

                                                                     O. Sepals and petals numerous, the series often not

                                                                              sharply differentiated. Plants spiny usually

                                                                              fleshy .....................................................Opuntiales

                                                                   OO. Sepals and petals usually 4 or 5. Plants not

                                                                              fleshy, rarely spiny.

                                                                              P. Ovules several to many in each locule (or

                                                                                        if 1 -2 the ovary superior and enveloped

                                                                                        by an hypanthium ..................... Myrtiflorae

                                                                            PP. Ovules 1-2 in each locule. Ovary

                                                                                         inferior.   Inflorescence   cymose or

                                                                                          umbellate ..............................Umbelliflorae

        

                CC. Petals connate and corolla deciduous as a single unit.

                        Q. Ovary superior.

                                  R. Stamens opposite the corolla tube as many as or more than

                                            corolla lobes.

                                             S. Placenlation free-central . Ovules usually many. Styles

                                                         one ..............................................................................Primulales

                                            SS. Placentation basal or the single ovule pendulous, the

                                                         styles or their branches ....................................... PIumbaginales

                                 RR. Stamens alternate with corolla lobes as many as the lobes or fewer.

                                              T. The corolla herbaceous, fruit never a circumscissile capsule

                                                           U. Corolla lobes convulute. Ovary 2 carpelled or

                                                                       ovaries 2 and each unicarpellate. Stamens

                                                                        usually inserted at or near corolla base

                                                                                         ..................................................... Contortae

                                                         UU. Corolla lobes imbricate. Ovary 1 with 2-5

                                                                        carples, stamens usually adnate to the mostly

                                                                         elongated corolla tube ............................... Tubiflorae

                                             TT. The corolla scarious. Fruit a circumscissile capsule

                                                                                   ..................................................... Plantaginales

                           QQ. Ovary inferior

                                       V. Stamens distinct, rarely coherent. Leaves opposite....................Rubiales

                                     VV. Stamens coherent or variously connate. Leaves mostly alternate

                                                  W. Carples 3. Placentation predominantly parietal flowers

                                                          mostly unisexual. Plant lianous herbs....................Cucurbitales

                                               WW. Carples usually 2 or 5 (rarely 3). Placentation axile

                                                           or ovules one and basal or pendulous. Plants

                                                           infrequently lianous herb ...................................Campanulatae

Order: Verticillatae

Family: Casuarinaceae

Vegetative characters:

1. Stem: woody, jointed.
2. Leaves: whorled, scale-like, united basally to form a toothed sheath.

Floral characters:

3. Inflorescence: male flowers in spikes, female flowers in heads.
4. Perianth: absent or represented by 2 scales.
5. Androecium: only 1 stamen.
6. Gynoecium: superior ovary, 2 carpels, one carpel aborted, parietal placentation.
7. Fruite: cone-like multiple fruit.
8. Seed: winged samara.

Order: Salicales

Family: Salicaceae

Vegetative characters:

1. Buds: winter; protected with scaly leaves
2. Leaves: with reticulate venation.

Floral characters:

3. Inflorescence: catkin, dioecious.
4. Flower: Unisexual.
5. Perianth: absent (naked flower), one or more glands present.
6. Androecium: 2-many stamens (male flower).
7. Gynoecium: Superior ovary, 2-4 carpels, 1 locule, parietal placentation (female flower).

Order: Urticales

Leaves simple, alternate, stipulate, flowers unisexual, androecium with few to several stamens, bicarpellate unilocular superior ovary with a solitary ovule.

Key to families of order Urticales

A. Fruit an achene

            B. Plants aromatic, erect or climbing…………………………………...……Cannabinaceae

            BB. Plants not aromatic, with stinging hairs…………………………………...….Urticaceae

AA. Fruit not an achene

            C. Fruit multiple, sap milky……………………………………………………...…Moraceae

            CC. Fruit a drupe, nut or samara, sap not milky……………………………………Ulmaceae

Family: Urticaceae

Vegetative characters:

1. Plant: Stinging hairs present.
2. Leaves: With reticulate venation.

Floral characters:

3. inflorescence: Dense small green cymose.
4. Flower: Unisexual, pentamerous  or tetramerous.
5. Perianth: is undifferentiated into calyx nor corolla, sepaloid.
6. Androecium: 5 or 4  antiposed stamens (male flower).
7. Gynoecium:Superior ovary, 1 carpel, 1 locule, basal placentation (female flower).

Family: Moraceae

Vegetative characters:

1. Plant: With milky sap.
2. Leaves: simple with reticulate venation, large stipules.

Floral characters:

3. Inflorescence: catkin, monoecious or dioecious.
4. Flower: Tetramerous, Unisexual.
5. Perianth: undifferentiated into calyx nor corolla, sepaloid.
6. Androecium: 4  antiposed stamens (male flower).
7. Gynoecium: Superior ovary, 2 carpels, 1 locule, apical placentation (female flower).

Order: Centrospermae (Curvembryeae)

The order is of interest as indicating a passage from Monochlamydeae to the Dialypetalous type. The simplest flower forms of Chenopodiaceae show a similar plan of floral structure to Urticales, while more advanced families are typically dichlamydous reaching in Caryophyllaceae.

The perianth biseriate, the monochlamydous type is represented by Chenopodiaceae and Amarantaceae. The embryo coiled or curved, thus the order has also been called Curvembryeae. The ovary superior and unilocular.

Key to families of order Centrospermae

A. Stem nodded, dichasially branched, leaves opposite……………………...…….Caryophyllaceae

AA. Not So

            B. Carpels 2 or more

                        C. Fruit achene

D. Fruite thin-walled………………………………..…………Nyctaginaceae

DD. Fruite inflated

            E. Perianth memberanous………………..……………Amarantaceae

            EE. Perianth herbaceous……………...……………..Chenopodiaceae

                        CC. Fruit capsule

                                    F. Perianth differentiated into K₂ and C _4-6……………..…….Portulaccaceae

                                    FF. Perianth single of 5 tepals…………………………...…………Aizoaceae

            BB. Carpel one

                        G. Perianth petaloid……………………………………..…………….Nyctaginaceae

                        GG. Perianth sepaloid………………………..…………...………….Phytolaccaceae

Family: Caryophyllaceae

Vegetative characters:

1. Stem: nodded, swollen nodes, dichotomously branched.
2. Leaves: opposite with reticulate venation.

Floral characters:

3. Flower: Pentamerous or tetramerous.
4. Perianth: differentiated into calyx and corolla.
5. Corolla: Petals are polypetalous, claw and limb, caryophyllaceous.
6. Androecium: 8, 10 stamens.
7. Gynoecium: Superior ovary, 2-5 carpels, 2-5  locules basally, 1 locule apically, axile placentation basally, free central apically, free styles 2-5, androgynophore present.

Family: Nyctaginaceae

Vegetative characters:

1. Leaves: with reticulate venation.

Floral characters:

2. Bract: Colored.
3. Flower: Pentamerous.
4. Perianth: Undifferentiated into calyx nor corolla, petaloid.
5. Androecium: 5-8 stamens, connate.
6. Gynoecium: Superior ovary, 1 carpel, 1 locule, basal placentation.

Family: Amarantaceae

Vegetative characters:

1. Leaves: With reticulate venation.

Floral characters:

2. Inflorescence: Dense small showy cymose.
3. Flower: Small dry pentamerous.
4. Bract: Colored, scarious, bracteoles present.
5. Perianth: Undifferentiated into calyx nor corolla, sepaloid.
6. Androecium: 5 antiposed stamens connate at base forming cup or tube.
7. Gynoecium: Superior ovary, 3-2 carpels, 1 locule, basal placentation.

Family: Chenopodiaceae

Vegetative characters:

1. Leaves: with reticulate venation.

Floral characters:

2. Inflorescence: Dense small green cymose.
3. Flower: Pentamerous.
4. Perianth: undifferentiated into calyx nor corolla, sepaloid.
5. Androecium: 5 antiposed stamens.
6. Gynoecium: Superior ovary, 2-3 carpels, 1 locule, basal placentation.

Family: Phytolaccaceae

Vegetative characters:

1. Leaves: with reticulate venation.

Floral characters:

2. Flower: Tetra- or Pentamerous.
3. Perianth: undifferentiated into calyx nor corolla, sepaloid.
4. Androecium: 4-5-∞ stamens.
5. Gynoecium: Superior ovary, 4-5-∞ carpels, 4-5-∞ locules, axile placentation, 

                           (may be apocarpous, basal placentation).