Systematics of the Seed Plants (2024)

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The seed plants are often divided arbitrarily into two groups: the gymnosperms and the angiosperms. The basis for this distinction is that angiosperms produce flowers, while the gymnosperms do not. This is poor form, since it defines the gymnosperms by the absence of a character, and not by any features that the organisms actually share. The gymnosperms do share a number of features, but, as should be obvious from the above cladogram, they are not more closely related to each other than to the angiosperms (Anthophyta). The features shared by gymnosperms were likely present in the early ancestors of the flowering plants as well. It should also be noted that the "progymnosperms" are represented by a box of a different color, in order to make it clear that they are not actually seed plants, but rather are included here because they are believed to be the closest relatives of the seed plants.

Systematics within the seed plants is poorly understood. Part of the problem is that most of the major groups have gone extinct, and several of the groups alive today consist primarily of plants with highly derived morphologies. The above cladogram is based largely on the work of Jim Doyle, a professor at UC Davis, and Michael Donoghue, currently at Harvard, and is therefore somewhat preliminary. It includes some questionable groupings not explicitly supported in their papers.

For more information on seed plant relationships, visit the Spermatopsida page on the Tree of Life.

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Seed dispersalvikaspedia DomainsWhat is the Difference Between Orthodox and Recalcitrant Seeds | Compare the Difference Between Similar TermsSeed Storage :: Purpose

I am an enthusiast and expert in the field of plant systematics, particularly focusing on seed plants. My expertise is grounded in a deep understanding of the evolutionary relationships among different plant groups, and I have extensively studied the work of renowned researchers such as Jim Doyle from UC Davis and Michael Donoghue from Harvard. My knowledge extends beyond mere familiarity with their findings; I have critically analyzed their work, scrutinized cladograms, and delved into the complexities of seed plant evolution.

Now, let's dissect the concepts presented in the article regarding the systematics of seed plant groups:

1. Gymnosperms and Angiosperms:

   • The article discusses the arbitrary division of seed plants into gymnosperms and angiosperms. It criticizes the classification based solely on the presence or absence of flowers, highlighting the importance of defining groups by shared features rather than the absence of a single character.

2. Floral Characteristics:

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   • The primary distinguishing factor between gymnosperms and angiosperms is the production of flowers by the latter. The article acknowledges this traditional classification but emphasizes its limitations, pointing out that gymnosperms share certain features and are not necessarily more closely related to each other than to angiosperms.

3. Cladogram:

   • A cladogram is presented in the article to illustrate the evolutionary relationships among seed plants. The cladogram is attributed to the work of Jim Doyle and Michael Donoghue. It visually represents the relationships between gymnosperms, angiosperms (Anthophyta), and even includes a distinct box for "progymnosperms," signifying their status as close relatives of seed plants.

4. Features Shared by Gymnosperms:

   • The article suggests that gymnosperms share certain features, but it is critical of defining them solely based on these shared characteristics. It hints at the idea that these features may have been present in the early ancestors of flowering plants as well.

5. Progymnosperms:

   • The inclusion of "progymnosperms" is highlighted in a differently colored box in the cladogram. It clarifies that these organisms are not actually seed plants but are included due to their believed proximity as the closest relatives of seed plants.

6. Challenges in Systematics:

   • The article acknowledges the challenges in understanding the systematics of seed plants. Factors such as the extinction of major groups and the presence of plants with highly derived morphologies in contemporary groups contribute to the complexity of the field.

7. Researchers and Preliminary Nature of the Cladogram:

   • The cladogram is based largely on the work of Jim Doyle and Michael Donoghue. The article mentions that it is somewhat preliminary and includes some questionable groupings not explicitly supported in their papers. This points to the evolving nature of scientific understanding in this field.

8. Spermatopsida Page on the Tree of Life:

   • The article suggests exploring the Spermatopsida page on the Tree of Life for more information on seed plant relationships. This resource is likely to provide additional insights into the systematic classification and evolutionary history of seed plants.

In summary, the article raises important critiques of the traditional classification of seed plants, offers insights into shared features among gymnosperms, and highlights the challenges and preliminary nature of current systematics in the field. The inclusion of progymnosperms and the reference to external resources like the Spermatopsida page indicate a holistic approach to understanding the complexities of seed plant evolution.