| Habitat | This species occurs in a wide array of habitats, some a bit weedy. It occurs in open bottomlands and edges, woodland borders, thickets,and in glades. It is less of a rich and moist soil species than is S. hebecarpa and can grow in some circumneutral soil sites. It also tends to be found more in disturbed babitats than does S. hebecarpa, such as sewerline clearings and other recently disturbed places. Because these two species are so similar in appearance, habitat distinctions are not overly clear, and certainly one cannot separate these two simply by habitat. |
| Identification | This is one of two native species in the genus Senna that were formerly in the genus Cassia, with some other obviously different species. This is a fairly tall and robust species, growing erectly and to about 4-5 feet tall, rarely to 6 feet tall -- somewhat more robust or taller than S. hebecarpa. Though essentially unbranched, it has very long leaves that make the plant appear branched and bushy. The leaves can be 10-12 inches long, and they are highly divided into 10-20 fairly large leaflets. Each leaflet is roughly elliptic and about 1.5 inches long and about 0.5-inch wide, thus about 1/3rd as wide as long. (S. hebecarpa is essentially identical in these features.) In this species, there is a small globe- or dome-shaped gland in the leaf axils, and this gland has such a tiny stalk that it is practically not visible; in S. hebecarpa, these glands are slightly stalked and slightly narrower than tall, but this is subtle and difficult to use as a separation character. The inflorescences of both species are also extremely similar; each has showy clusters of racemes in axils and at the summit of the stem. These flowers are quite large, bright golden-yellow and about 1 inch across. (There might be slight differences in the flowers or pattern of inflorescences, but these are not mentioned in various keys.) To be certain, you must have the pods present, and it is better to have some familiarity with one or the other species to feel comfortable. The pods of S. marilandica differ in three ways: 1) they are 8-11 mm wide (about 2/5-inch), as opposed to quite narrow, from 5-8 mm wide (about 1/4-inch), in S. hebecarpa; 2) it is essentially glabrous, as opposed to quite hairy (at least at early maturity) in S. hebecarpa; and 3) the many segments of the pod are rather narrow (wider than long), as opposed to square-shaped (about as long as broad) in S. hebecarpa. It should be mentioned that the shape of the pod segments can be tricky to judge without familiarity with both species, and the hairiness of the pods of S. hebecarpa can depend on fresh or old pods. Also, pods that are rather immature are obviously going to be smaller than when mature, and thus a developing pod of S. marilandica, when measured, may well be less than 8 mm wide. Thankfully, neither species is truly rare in the state, and ranges are somewhat similar, and thus mistaken identity when in the field is not overly critical, other than collecting one for an herbarium and getting the incorrect identification. However, it is quite important in establishing new county records for each. Field biologists often run across a few of these two species annually in their work, such as along greenways while walking in bottomlands, or along wet thicket margins; when in bloom, they are absolutely impossible to overlook. But, you almost certainly should re-visit the site(s) later in summer or fall, and identify the plants by the pods and not by flowers or glands. | |
