Results 1. For each phylum of seedless vascular plants, describe those characteristics that are similar for both living specimens and fossils. For example, do you observe dichotomous branching and similar shape and form of leaves, stems, or sporangia? Refer to the living specimens or your sketches. Lycophytes: Sphenophytes: Ferns:

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### Lycophytes

- Both living and fossil lycophytes exhibit small, simple leaves called microphylls, which are typically arranged along the stems.
- The stems often show **dichotomous branching**, meaning they repeatedly split into two roughly equal branches.
- Fossil specimens display similar arrangements of sporangia (spore-producing organs), often positioned along the margins or in distinct clusters, resembling those in living species.

### Sphenophytes

- Living sphenophytes (such as those in the genus $$ Equisetum $$) and their fossil relatives both have segmented, jointed stems with distinct nodes and internodes.
- The overall body plan—with whorls or reduced, small leaves—is consistent between fossils and extant plants.
- Reproductive structures in both fossil and living sphenophytes are arranged in cone-like or strobili clusters, indicating similar sporangial organization.

### Ferns

- Fossil and living ferns share a similar frond structure, typically exhibiting pinnate (feather-like) arrangements of leaflets.
- The branching pattern of the vascular tissues in the fronds is often dichotomous or exhibits a reticulate (net-like) arrangement, which is consistent across the fossil record and modern forms.
- Both groups produce sporangia on the undersides of their fronds—often grouped into clusters called sori—with similar shapes and arrangements, reinforcing a shared reproductive morphology.

### Lycophytes - Both living and fossil lycophytes have small, simple leaves called microphylls along their stems. - They show **dichotomous branching**, where stems split into two equal parts repeatedly. - Sporangia are arranged similarly, often along the stem margins or in clusters. ### Sphenophytes - Living and fossil sphenophytes have segmented, jointed stems with distinct nodes and internodes. - They have a consistent body plan with reduced, small leaves arranged in whorls. - Reproductive structures are cone-like or strobili clusters, similar in both forms. ### Ferns - Both fossil and living ferns have fronds with pinnate (feather-like) leaflets. - Their vascular tissues branch dichotomously or in a net-like pattern. - Sporangia are located on the undersides of fronds, grouped into sori with similar shapes and arrangements.

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