Skunk Cabbage

Symplocarpus foetidus

Araceae Family. Arums or aroid family: Jack in the Pulpit is a temperate relative and Elephant’s Ear a tropical relative. See below

This unusual plant has something to find all year and is difficult to describe. It took a lot of reading and observing to figure out what was what. I went back again and again and finally got stung by some ground nesting bees when I was photographing a seed I found for the first time. Exciting and painful. I put a glossary at the bottom that helped me see more. Lot’s of new words for me.

Upper Left: Spring leaves expanding above the mottled spathe that wraps itself around a flower cluster (detail on right); Center: Before the leaves expand the flower cluster (spadix) is protected by the open spathe. Pale blue modified leaves protect new growth; Bottom: fruit on ground next to a seed and decomposed leaf; Left: seed with new roots and shoot.

Habitat: Shallow wooded wetland covered with emerging skunk cabbage leaves in spring. This is where I got stung. Because there are such huge colonies, I was surprised to find out they only reproduce from seeds and not vegetatively (clones).

Roots: Contractile, fleshy roots pull plants into the ground and vertically orient new shoots. I don’t usually see Skunk Cabbage roots but noticed some in an old photo after I read about them. They widen and then contract lengthwise every season to anchor Skunk Cabbages in a shallow, wet habitat.

Shoots (Stems and Leaves) Leaves on top of a vertical rhizome (underground stem) form a basal rosette. They radiate out (rosette) and appear to grow out of the ground (basal). New green leaves emerging (below) from two pale blue protective leaves. Some call this convolute vernation (open with overlapping sides). The word vernation is an old term that describes different ways new leaves open.

They also have pinnate venation, not vernation, unusual for a monocot. The lateral veins are arranged like a feather extending out from the midvein and not parallel to it. The veins are in relief when you can see the back of the the leaf.  (below).

Below Left: After the leaves create enough sugars to store in the  rhizomes for next year, they start to decompose. Right: In winter you might find these pale modified leaves that some call stipules because they are so different.

Flower (spathe and spadix)

Spathe: A typical flower has 4 whorls from the outside to the inside: sepals, petals, stamens and pistils. The outside sepals usually protect new growth. A skunk cabbage is anything but typical. Instead one bract protects the entire flower cluster called an inflorescence. A bract is a term used when a flower has “extra” parts that are hard to define using the 4 whorls. This bract is unique to the Araceae family and has a special name (spathe). Left below: a mottled spathe emerging between winter leaves. Right: The spathe surrounds the spadix, a cluster of flowers crowded together on an axis.

Spathe color variations

Flower parts: Back to the 4 whorls. The two outer whorls, sepals and petals, grouped together are called the perianth. When the petals and sepals look the same, they are called tepals (like a tulip). Skunk cabbages don’t need protective sepals because the spathe does that. They don’t need “attractive” petals because the pollinators are attracted to the heat (thermogenesis) and a fetid odor the plants produce in early spring. The specific epithet or species name foetidus is Greek for foul odor. The sepals and petals seem to be fused into 4 fleshy “somethings”. I see the words sepals, petals, perianth or tepals used in different sources struggling to describe these fused whorls.

Female Stage of a Skunk Cabbage: The female part of a typical flower is a pistil that includes 3 parts: the ovary, style, or neck,  that raises the stigma that receives pollen. In a Skunk Cabbage it is hard to see these parts. Stamens are usually the 3rd whorl described. But I put the pistils now because they ripen (are ready to receive pollen) before the stamens. This is called protogeny and helps to prevent self-pollination.

Left below: spathe removed to see the spadix which is a cluster of flowers (inflorescence). Each individual flower (floret) has 4 flat “somethings” (sepals, petals, tepals, or perianth) with a pointy stigma showing. No stamens yet. Right: I drew white lines around a few single florets.

Below left: a single floret. Below right: a cross section of the spadix at this stage showing the fleshy axis with immature ovaries (that hold the seeds) attached and topped by the stamens that haven’t emerged yet (3-1-18).

Male stage of a skunk cabbage: A typical flower’s male parts are called stamens that usually include filaments (stalks) and anthers (pollen holders). Left below: The stigmas can still be seen on the lower flowers. The closed anthers start to emerge and surround the stigma on the upper florets. Right: 4 clustered extrorse anthers on fat filaments before they dehisce (open to release pollen). Extrorse means they release pollen away from the axis.

Fruit: After the flowers have been pollinated, the peduncle (flower stalk) lengthens and the spathe and spadix fall over. The leaves are expanding.

Below: individual floret parts with 4 flat tepals and a pointy stigma in the center together form a subglobose (almost round) compound fruit. Symplocarpus is from Greek “symplo” meaning connection and “carpos” meaning fruit. These fruits are so bizarre and unusual. This compound or multiple fruit is formed from the ovaries of several individual florets that ripen into small fruits fused together into a larger fruit.

Below: the leaves, petioles (leaf stalks), peduncles (flower stalks) and spathe decompose. What’s left is the compound fruit. When the spadix finally decomposes the seeds are exposed. And undergtound bees make their nests on the ground there. I should have photographed them but I was occupied by running away.

Tropical Relative: Elephant’s Ear Alocasia portora painted in the Wellesley College Botanic Garden’s old greenhouses. Notice the spathe and spadix

Botanical definitions: words that helped me see more

Monocots: often described with one cotyledon (seed leaf) inside their seeds, parallel-veined leaves, flower parts in multiples of 3s, fibrous roots and underground storage organs like rhizomes. Skunk cabbages do not have parallel veins and has flower parts in multiples of 4. I love it when plants don’t follow our rules.

Roots: Contractile roots are wrinkled roots help pull plants into the soil.

Stem: A rhizome is an underground stems where new growth happens. It sits vertically on top of the roots in a Skunk cabbage. Most rhizomes are horizontal. The above-ground stem is tiny and surround by basal leaves.

Leaves

• Ovate, cordate (almost oval shape with a heart-shaped base)
• Petioles: leaf stalks. These start out short and fat, lengthen during the summer and finally decompose into a black goo.
• Stipules: modified leaves. Some use this term to describe the light blue leaves that protect next year’s Skunk Cabbage plants.
• Vernation: how new leaves expand in spring.
  • Convolute vernation: rolled up longitudinally with overlapping edges.
• Venation: how the leaf veins grow
  • Pinnate venation (like a feather), unusual for a monocot that usually has parallel veins.

Flowers: (standard flower: sepals, petals, stamens, pistil)

• Spathe: Modified leaf  or bract that surrounds the clustered flowers. Partly underground, w/ short peduncle (flower stalk) that lengthens and eventually falls over after it is pollinated.
• Spadix: cluster of small, stalkless, flowers closely arranged around a fleshy axis. A stalkless cluster of flowers is also called a spike. Spadix is a term used for the characteristic spike of the Araceae family.
• Inflorescence: a cluster of connivant flowers that cover the spadix.
  • Connivent: converging or coming together but not organically united.
  • Florets are the individual flowers of the spadix.
• Perianth: sepals and petals grouped together.
  • Sepals: Fleshy and flat, in a skunk cabbage these never unfold to expose the other parts as in a typical flower.
  • Petals: Skunk cabbages attract pollinators with smell and heat, so they don’t need “attractive“ petals.
  • Tepals: when sepals and petals look similar. I love the fact that the experts struggle to define what appear to be petals in the skunk cabbage. In any case, there are 4 of them.
• Perfect flowers have both male (pollen) and female (seed) parts
• Stamens: extrose anthers that dehisce longitudinally (they open to the outside lengthwise away from the axis to release pollen. They sit on the fat filaments or stamen stalks.
  • Androecium. All of the stamens collectively. Some of the older references use this term when they describe the stamens.
• Pistil: female reproductive organ (ovary that protects the seeds), style or neck that raises the stigma up to receive pollen. In a skunk cabbage the style and stigma look like a cone where we can only see the tip or stigma.
  • Gynoecium. All the pistils collectively.
  • Protogynous: the stigma ripens before the anthers release pollen. This helps prevent self-pollination. Pro means beforehand in Latin.

Fruit

• Fruit: ripened ovary with seed inside.
• Compound fruit: Two or more like parts in one organ that protects seeds.
• Infructescence: a cluster of fruits
• Multiple fruit: an inflorescence or flower cluster, each floret with a separate ovary, develops into separate fruits fused together into a larger fruit.
• Subglobose: sub means almost or almost round