Integrative Biology 335:
Systematics of Plants

Magnoliaceae, Ranunculaceae, and Papaveraceae

Announcements:

Your second lecture assignment is due in class on Monday, February 23. Click here for more information about the assignment. You will also need to refer to the lecture notes on the Methods and Principles of Systematics. This assignment is worth 2% of your final grade. Answers will be posted in the lab (Tuesday, Feb. 24th). The grading scheme is available here for downloading, in PDF format.

Text and Other Resources:

In the textbook Plant Systematics, A Phylogenetic Approach by Judd et al., Third Edition, read the material on these pages:

  • Magnoliaceae, pp. 237 – 239
  • Ranunculaceae, pp. 309 – 312
  • Papaveraceae, pp. 314 – 316

BE SURE to go through these three families in Digital Flowers.

General Objectives:

After studying this material you should be able to:

  1. Explain the relationships among the major angiosperm groups, such as the eudicots, monocots, magnoliids, and the ANITA grade.

  2. Know the plesiomorphic (i.e., ancestral) angiosperm features characteristic of members of the ANITA grade and magnoliid clade.

  3. Know the most important diagnostic features of the three families and be able to compare and contrast their most important features.

Angiosperm Phylogeny Overview:

  • Traditional classification system of flowering plants, by Arthur Cronquist of the New York Botanical Garden, where the Class Magnoliopsida is divided into six subclasses, with the Magnoliidae being the most basal.

  • The relationships among the major angiosperm groups used in your textbook are modeled after the system of the Angiosperm Phylogeny Group II (APG II)

  • Most angiosperm species fall into one of two groups: monocots (single cotyledon, pollen grains usually monosulcate [meaning, a single, long aperature]), and eudicots (two cotyledons, pollen grains usually tricolpate [meaning, three long, grooved aperatures]). The monophyly of each of these two groups is supported by several other synapomorphies (see text fig. 9.1).

  • The monocots and eudicots are derived from members of a morphologically disparate, paraphyletic group of families.

  • Most recent molecular analyses support the position of Amborellaceae, Nymphaeaceae, and Austrobaileyales (Illiciaceae, Trimeniaceae, Austrobaileyaceae) as the earliest diverging lineages (also known as the ANITA grade).

  • Members of the ANITA grade have probably retained many plesiomorphic (ancestral) angiosperm characteristics. Members of this grade have their carpels usually sealed by a secretion; some members lack vessels (specialized water conducting cells).

    Other features include:

    • perennial, woody, evergreen habit
    • alternate, simple, pinnately veined leaves with entire margins
    • no stipules
    • actinomorphic, perfect, hypogynous flowers
    • floral parts numerous, spirally-arranged, distinct and free
    • perianth of tepals
    • stamens poorly differentiated into an anther and filament
    • apocarpous gynoecium, marginal placentation
    • insect pollinated

  • Most of the remaining angiosperms constitute the magnoliid clade, or the Magnoliids.

  • The diversity of flowering plants is not evenly distributed:
    • Eudicots clade (75% of angiosperms)
    • Monocots clade (23% of angiosperms)
    • Magnoliid clade (2% of angiosperms)
    • The remaining major clades contain a little over 250 species in total (less than 0.1% of flowering plant diversity)

Magnoliids or Magnoliid Complex: Family Magnoliaceae

The magnoliids are made up of four orders. The Magnoliales contains six families, of which we will cover only the Magnoliaceae.

Magnoliid Clade = Magnoliaceae

The magnoliids have a number of unspecialized features (they are "low tech" plants). During the semester (and especially when working on Lecture Assignment II), compare features of other plant families to those of the Magnoliaceae, and you will see derived or specialized features. The magnoliids, along with the morphologically similar members of the ANITA grade, are considered to have retained the greatest number of plesiomorphic features within the angiosperms.

Here are some generalizations about magnoliids; remember, there are always individual exceptions.

  • Leaves often alternate, simple, entire
  • Perianth well developed, petals not connate
  • Stamens numerous, not connate or adnate, often laminar
  • Pollen grains monosulcate (boat-shaped with one aperture)
  • Carpels usually numerous and not connate
  • Unsealed carpels found in some members (as in Drimys winteri)
  • Floral parts spirally arranged (or sometimes in whorls of three)
  • Many have aromatic oils (characteristic secondary chemistry)
  • Primarily woody, but some herbs
  • Wood can lack vessels
The magnoliids are more closely related to the monocots and eudicots than they are to members of the ANITA grade

Family Magnoliaceae

Eudicots or Tricolpate Angiosperms: "Basal Tricolpates": Families Ranunculaceae and Papaveraceae (order Ranunculales)

  • These plants are called the tricolpate angiosperms in reference to the main morphological character marking this group--namely, the occurrence of pollen grains with three colpi, or germinal furrows

  • The Eudicots comprise the early diverging "basal tricolpate" lineages, containing such families as Ranunculaceae and Papaveraceae, and the core eudicot or core tricolpate clade

FAMILY COVERAGE:

Ranunculaceae

Papaveraceae

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