University of Guam

[ Pinophyta ] [ Angiosperms ]

Angiosperms

An aster (euasterid: campanulid), possibly Doronicum; note the dicot venation in the leaves.  (Photographed in Austria)

On this page:  On-line sources;   Classification;     Some key flower terms   

On line Sources 

There's an incredible amount of information about flowering plants on the web, reflecting the fact that most of the plants we use for food, shelter, decoration, etc., are angiosperms. Most of the links below are to portals, which have organized collections of links. I have put more specific links on the families pages under each of the two Classes (Liliopsida and Magnoliopsida: buttons on the left).

Taxonomy / systematics:
Flowering Plant Gateway - Various paths for exploration or comparison of 3 major flowering plant classification systems - from Texas A&M Univ. The selection options provide various paths for exploration or comparison of three major systems of flowering plant classification and links (over 7,000), via selection of the Family name.
Internet Directory for Botany -- Plant Families portal.
Open Directory Project: Liliopsida -- monocots organized by family.
Open Directory Project: Magnoliopsida -- dicots organized by family.
Systematics: UC Museum of Palaeotology
Hugh Wilson's Texas A&M Plant Systematics schedule with links to the families he covers. His Flowering Plants overview gives a succinct summary of characteristics and evolutionary relationships.

Moore, P.H. & P.D. McMakin. 1979. Plants of Guam. UOG-CALS. Vascular terrestrial plants. This book has been updated and put on line by J. McConnell.

Structure/ plant anatomy:
The Virtual Plant: plant anatomy practical course on line (CEJ Botha, Rhodes U., South Africa)
The Plant Body: a slide presentation that summarizes the basic structure of flowering plants. (E. Levitin, U. Tulsa)
Secondary tissue development   

Classification

Soltis & Soltis (2004) recognize the phylogenetic groups within the angiosperms as follows:

 Basal angiosperms
            Amborella
            Nymphaeaceae
            Magnoliids: Magnoliaceae
            Monocots (Arecales, Poales)
    Eudicots
             Early-diverging eudicots (Ranunculales, Proteales, etc)
             Core eudicots
                   Asterids
                      euasterids I = lamiids (Lamiales, Solanales, etc.)
                      euasterids II = campanulids (Asterales, Ericales, etc.)
                   Rosiids
                       eurosids I = fabids (Fabales, Cucurbitales, Rosales, etc.)
                       eurosids II = malvids (Brassicales, Malvales, etc.)
                    3 other orders

In this course we will study Soltis & Soltis (2004) to examine the evidence for this phylogeny (much of it reported in the last 10 years), and the large questions that are still unclear. Also access the Angiosperm Phylogeny Group website (Missouri Botanical Gardens) for current phylogenetic trees and detailed information.

The classical systematics is shown below; in this system all flowering plants are either monocots (Liliopsida) or dicots (Magnoliopsida)--there is no division into "true" dicots and other dicots. List is from James D. Mauseth, 1998, Botany, 2e. Jones & Bartlett Publ. (follows Cronquist, 1981, Classification of Flowering Plants); this book gives an excellent account of the Classes and Orders of Magnoliophyta. Families with boldface hyperlinks are the ones we will look at in Plant Diversity.  You do not need to remember the subclasses, but here there are for reference. For online descriptions of the subclasses, click the [description] links, which take you to the University of Wisconsin, Madison, plant systematics pages. Each of these subclass pages in turn has links down to the families within each one and to the Classes above.  Each of their family pages gives the floral formula at the top, as a diagram linked to the key that explains these formulae.  Another source that I have linked to in the family pages is Manhart's Plant Taxonomy Course at Texas A&M.

Division Magnoliophyta

Class Liliopsida (monocots)

Subclass Alismatidae (various aquatic plants including our seagrass Enhalus) [description]

Subclass Arecidae  (palms and aroids; Cocos; Philodendron; taro) [description]

Arecaceae [Palmae]

Subclass Commelinidae (grasses & sedges; Tradescantia, Rhoeo)

Poaceae

Subclass Zingiberidae (gingers; bromeliads; banana) [description]

Subclass Liliidae (lilies, orchids; yucca, agave; yams) [description]

Orchidaceae

Class Magnoliopsida (dicots)

Subclass Magnoliidae (magnolia; poppies; etc.) [description]

Subclass Hamamelidae (walnut; hops and hemp; oaks....) [description]

Subclass Caryophyllidae (cacti; buckwheat; bougainvillea; spinach)  [description]

Subclass Dilleniidae (hibiscus; violets; passionflower; squashes; heather)  [description]

Malvaceae, Brassicaceae [Cruciferae], Cucurbitaceae

Subclass Rosidae [114 families!] (roses; legumes; euphorbs; grapes; carrots....) [description]

Fabaceae [Leguminosae]

Subclass Asteridae (daisies; tomato; mint; morning glory....)  [description]

Solanaceae,  Asteraceae

Double fertilization as seen in prepared slide of Lilium (in this genus three of the 
original megaspore nuclei fuse to give 3n nuclei at the chalazal end.

Some key flower terms

Flowers modified strobili which may have anthers (microsporangia) and/or ovaries (contain megasporangia within ovules). If they have both, the flowers are described as perfect, if only one, imperfect. This has nothing to do with whether the other two possible parts -- sepals and petals -- are present. If all are present the flower is complete, else incomplete. A flower can be perfect and incomplete, but if it is complete it must also be perfect. If it has only stamens the flower is called staminate (see squash flower in the photo below), if only pistils, pistillate. Flowers are sporophyte structures, and therefore are not "male" and "female". Only the gametophytes they bear are male and female. The male gametophyte is the pollen, the female gametophyte is the ovule. The male gametophyte is within the spore wall, the ovule has cell layers around it that are interpreted as being equivalent to the spore wall. Remember, seed plants are functionally heterosporous.

Imperfect and perfect flowers. (Left) Cutaway staminate squash flower (Cucurbitaceae). 
There is a cluster of stamens but no carpels (the pistillate flower has a "baby" squash 
just below the sepals). This imperfect flower has fused petals. (Right) An oat flower, 
typical of grasses (Poaceae) and other wind-pollinated plants, lacks petals, and has
bracts instead of sepals to protect the flower bud. This tiny flower is perfect. The yellow
anthers are visible, and the feathery structures are the stigma/styles of the carpels.

Anthers are usually on the ends of filaments and the whole structure is a stamen. Ovules are within ovaries or carpels (a.k.a. pistils), which extend out with a style and stigma (the latter traps the pollen). If there are several carpels, they may be separate or fused. Ovaries may be superior or inferior. This is a position, not an attitude!  Anthers may be fused together, or partially fused to the carpels (look at a hibiscus flower). [We will not use floral formulas in this course; if you want to refer to these, see the U. Wisconsin links above.]

Sepals together are called the calyx. The ring of petals is also called the corona. Both together = the perianth. You will see these words but you do not need to know them for this course.

Dissection of a pea flower to show ovules in the ovary (peas in the pod), at the time of pollination.
Pea flowers are complete, but the sepals are not evident in this photo.