Sewanee’s Basal Angiospems

There are several groups of angiosperms – flowering plants – that branched off from the phylogenetic tree earlier than did monocots or eudicots. They possess characteristics of both groups, and they are commonly known as basal angiosperms. Further genetic work is needed to understand the relationships among these families, and there remains disagreement on which groups are most basal. For the sake of our flora, we consider 7 families present on the Domain as descendants from this primitive group. We have found 14 taxa in these families:

Watershield

Starting with a perennial rhizomatous aquatic plant in the family Cabombaceae (Order Nymphaeales) Water shield (Brasenia schreberi) is a native floating plant with an oblong olive green leaf. Purple flowers emerge in the summer, where it is wind pollinated. Water shield can form thick clonal carpets, making it a pest in waterbodies, such as our Lake Bratton.

SnakerootThe next family we will examine is the rhizomatous Aristolochiaceae (Order Piperales). These perennial herbaceous plants often take the form of vines with broad leaves and peculiarly shaped flowers. The flowers give off a foul odor which attracts insects to it, thereby aiding in pollination. Little brown jug (Hexastylis arifolia var. ruthii) has arrow-head leaves and a flower that appears at the base of the plant on the forest floor, resembling a brown jug. You can find it in moist areas on north-facing slopes in the coves, such as in Dick Cove. Canada wild ginger (Asarum canadense) has a reniform leaf and bowl-shaped reddish-brown flowers with light colored hairs. It is also associated with streams, and has been found along them in Shakerag Hollow and Dick Cove. Virginia snakeroot (Aristolochia serpentaria) and Pipevine (Aristolochia macrophyllum) are also present in coves on the Domain.These toxic plants have been used in traditional medicine to aid in childbirth and treat snakebites.

Lizard's tail

The Saururaceae (Order Piperales) consist of herbaceous aromatic plants that are associated with water edges. Lizard’s tail (Saururus cernuus) has long heart-shaped leaves and a long flower spike with white flowers in the summer. Look for it on the edges of Lake Bratton.

SweetshrubThe Calycanthaceae (Order Laurales) are aromatic deciduous shrubs. Sweetshrub (Calycanthus florida) has broad opposite leaves and produces fragrant dark red flowers. The bark and twigs are also strong smelling, making it a popular plant for traditional native gardens. We spotted this shrub flowering while exploring Fall Creek Falls in May, and you can find it near Morgan’s Steep or in Dick Cove in a mixed oak-hickory habitat.

20150528_165746Lauraceae (Order Laurales) are typically aromatic trees and shrubs and often evergreen, though our species are not. Cinnamon and avocado are in this family, and drupes are animal-dispersed. Northern spicebush (Lindera benzoin) is a clonal shrub with oblong leaves. Flowers are small, yellow, and clustered. The fruits are red berries. Northern spicebush has been spotted below Green’s View and near the War Memorial Cross. Sassafras (Sassafras albidum) is another common deciduous shrub, though it can become a small tree. It also produces small yellow flowers, which become ripe blue fruits The leaves are characteristically mitten-shaped, and turn bright yellow, red, and orange in the fall. Sassarfas is common in oak-hickory forests on top of the Cumberland Plateau, and can also be found in the cove. Spicebush swallowtail (Papilio troilus) lays eggs on both species.

Southern MagnoliaTulip treeThe Magnoliaceae (Order Magnoliales) are insect-pollinated trees and shrubs. The floral axis is cone-shaped, and petals and sepals are undifferentiated. Flowers are perfect, and flower parts are arranged spirally. Our native magnolia is the deciduous Cucumber tree (Magnolia acuminata). Native to the Appalachian Mountains, this tree has pointed leaves and yellow flowers. Fruits resemble a cucumber when immature, but mature to be red. Find our native magnolia in Shakerag Hollow and Lost Cove. We have two planted magnolia species which are spreading, but not native to the Domain. These are Southern magnolia (Magnolia grandiflora) and Bigleaf magnolia (Magnolia macrophylla). Southern magnolia has dark, evergreen leaves and large white flowers. Bigleaf magnolia is easily recognizable by its deciduous leaves which are the largest of all native North American species. Another easily recognized member of this family is the Tulip tree (Liriodendron tulipifera). Tennessee’s state tree is tall and fast-growing with four-lobed leaves. In May, it produces flowers which are yellow-green with an orange band. Look for the tulip tree in disturbed areas; it is common on both the top of the plateau and in the cove.

Pawpaw

The Annonaceae family (Order Magnoliales) is commonly found in the tropics. Pawpaw (Asimina triloba) is a clonal understory tree. Leaves are lanceolate and often droop from branches in overlapping arrangements. Leaves and flowers are odorous. Flowers are maroon with deep veins on their six petals; their smell attracts insect pollinators. The large oval edible fruits mature in the fall. You can find it in north facing slopes like Shakerag Hollow or in south facing slopes.

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About Callie Oldfield

I was a Post-Baccalaureate Fellow for the Sewanee Herbarium from Winter 2015-Summer 2016. I am currently a PhD student studying Plant Biology at the University of Georgia.

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