Integrative Biology 335:
Systematics of Plants

Asterid Clade continued
Asteraceae or Compositae

Announcements:

Comments on your second lecture exam have been posted on the General Course Announcements webpage. Your graded exam will be returned to you in lab tomorrow. Make an appointment to see Prof. Downie if you have questions or concerns.

Lecture quiz 9 is due in class today.

Text and Other Resources:

You are responsible for the following pertinent material presented in your textbook:

Also, view Digital Flowers

Course Objectives:

After studying this material you should be able to:

  1. Know the most important diagnostic features of the family Asteraceae, as well as features of the three traditionally recognized subfamilies.

  2. Know the major clade to which this family belongs and why.

Family Coverage:

Order Asterales (Asteraceae or Compositae), Campanulids Clade

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The order Asterales comprises some 12 families (whose relationships are still unclear) and about 24,900 species. The order is clearly monophyletic, as evidenced by a number of unique and diverse chemical characters, molecular data, and a plunger (or brush) pollination mechanism. Here, the stamens form a tube around the style, with the anthers opening toward the inside. Pollen is pushed out of this tube by specialized hairs on the style or by a specialized pollen-gathering cup. The style then elongates to present pollen to insect pollinators. Afterwards, the style branches spread apart and the stigmas become receptive.

Family Asteraceae (Aster, Composite or Sunflower Family)

The Asteraceae is the largest family of eudicots, with 1535 genera and 23,000 species. It is obviously monophyletic and easily recognized. It is divided into 17 tribes and, sometimes, three subfamilies. It comprises 10-20% of a flora of any given area.

Compositae, alternative name. A "composite" of small flowers (=florets)

Digital Flowers for family coverage

Inflorescence, fruit, habit and leaves from Class Notes

Flowers and Floral Formula from Class Notes

Examples from Class Notes: Radiate, Discoid and Ligulate Capitula

Drawings 1. Parts of a radiate capitulum and disc florets (to label in Class Notes)

Drawings 2. Three different kinds of florets and capitula (to label in Class Notes)

Pappus illustrations Pappus (=highly modified sepals) may consist of scales, awns, or bristles (or be absent)

Zomlefer text illustration-1 (Radiate capitulum)

Zomlefer text illustration-2 (Discoid and Ligulate Capitula)

Fig. 9.140 Judd et al. text, Radiate Capitula

Fig. 9.138 Judd et al. text, Discoid Capitula

Fig. 9.139 Judd et al. text, Ligulate Capitula

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