Silkgrass

A plant named "silkgrass" conjures up images of flashing silver, shining green, the play of light and shadow. Who would relegate such a plant to, "you still here?" status? Who else but yours truly, who never really took it seriously before looking at it close up recently. Although it may flower intermittently throughout the year, silkgrass, like many other members of the Aster family, blooms most heavily in fall. It has been showy for several weeks now (we're starting 2nd week of December) and shows no signs of slowing down.

Pityopsis graminifolia - Narrowleaf Silkgrass

Narrowleaf silkgrass, Pityopsis graminifolia, is one of 4 species found in Florida, and the only species of silkgrass occurring naturally in SW Florida. It is very variable in size and vigor. Currently botanists recognize 5 varieties, though they are not always easy to distinguish from each other. In scrub it tends to stay low to the ground, intermingled with grasses. In my garden, where it doesn't get any special care, but still has a much more favorable habitat than scrub or sandhills, it is more or less upright, with leaves 12 -16 inches long.

Habit Sketch

The plant grows as a clump, with long, grasslike leaves at the base. A tall blooming stalk grows from the center of the clump. The leaves on this stalk are also grasslike, and diminish in size as you move up. By the time you are within 4-5 inches of the heads, they are reduced to scale-like bracts.

Pityopsis graminifolia reproduces by rhizomes and seeds. It does not seem troubled by insect or disease pests, and it attracts various pollinators. The ray flowers are a clear, bright, pure yellow. The heads last several days, and the stalks can be cut for indoor flowers. The silver appearance comes from tiny hairs that cover virtually the entire plant. The bloom stalk and its leaves tends to be even hairier than the long leaves. The hairs no doubt contribute to the plant's incredible drought tolerance. In the right light an entire clump will shine brilliantly, blindingly silver.

Inflorescence and Middle Part of Stem

The plant would benefit from staking while it is blooming, and part of the reason for my lack of respect is that I've watched it falling all over itself and other plants for  years instead of doing anything about its untidy habit.

Now that I am in the process of simplifying the garden because I'm getting too old and creaky to take proper care of what I've got, I'm thinking very positively about transplanting some of my clumps to some particularly dry and exposed troublespots in the yard. If I can get it established there I can let it sprawl and spread as much as it wants. Given the right space it can shine literally and figuratively. I'm anxious to see what it can do.

Emilia fosbergii - Weeds I Like

Since I've been fulminating against weeds, I thought I'd mention some of the ones I like. One of them is Emilia fosbergii, or "Florida Tasselflower." Since there's no grass to compete against, it comes up everywhere in the yard, but it is easy to pull, so I leave it where I like it, and pull out the rest. (Or not. I am a lazy gardener).The ones that  haven't yet gone to seed go into the compost pot. Pollinators like it too.

The top and the bottom of Emilia sort of don't match. Tall, thin stalks end in delicate nodding, drooping, sometimes upright heads of rose-red disc flowers(more on this later). The anthers (pollen-bearing structures) and pollen are bright orange-yellow. The heads are around a half-inch long or a little more, depending on where the plant is growing, and about a quarter-inch wide at the base. The bottom of the plant on the other hand, is robust and vigorous.

Vigorous Bottom Portion of Plant

The stems and new leaves can be intensely hairy. Older leaves and "sepals" (phyllaries) show varying degrees of hairiness. The way the heads seem just to float above the foliage would make Emilia a nice plant to include in a mixed border. A larger plant with 8-10 flowering stems could even have the honor of a place in front, but since Tasselflower is a weed, its growth can be unpredictable. The flowering heads can be anywhere from 4 -to - 6 inches above the ground in young plants, up to around 20 inches above ground on older, larger plants. Growing conditions also affect the size and number of flowering stalks. The plants deteriorate after they set seeds. I haven't tried dead-heading to see whether I could prolong blooming, because the plant self-sows so vigorously.


The growth form of the plant is pretty cool. The first leaves on the stem are quite different from those farther along. They are roughly the shape of an inverted triangle on a long thin stem. The "stem" is actually not a petiole, but an extremely narrowed part of the leaf blade itself. As you move up the plant you get  intermediate leaf stages with increasingly shortened "stalks." The leaf itself becomes more oblong, and eventually arrow-shaped. At first glance it looks like the stem punches through the higher-up leaves, but a closer look shows that the base of the leaf clasps the stem.

Another leaf clasping a stem is formed between the "old" leaf and the main stem. This smaller leaf gradually enlarges to full size as the stem new itself grows longer. In the drawing below you can see the tiny leaf just to the right of the caption. The new stem elongates while the leaf enlarges, until you get the structure in the right hand of the drawing, in which the leaf and stem appear "on top" of the older leaf.

Another species, Emilia sonchifolia, "Lilac Tasselflower," occurs much less frequently in the yard. In general it seems a more diminutive and less vigorous plant, but that may be a function of its environment. The disk florets are a beautiful purple-pink instead of red. It is less common than its red cousin. According to the USDA Plants Database website, Emilia fosbergii occurs in Florida, Georgia, Louisiana, Texas and California. Its origin is unclear, with Asia, Australia, and South and Central America all listed as possibilities.


Emilia is a member of the Aster family. What many people (and I used to be among them) think of as a single flower in this family is actually a conglomeration, or composite, of individual flowers or florets, called a "head." This might seem like a trick the botanists have come up with to  keep us amateurs out, but it actually makes sense once you start really looking hard. The things that look like petals are "ray florets," and the things in the middle are "disk florets." The first drawing, on the left, shows the entire head, with ray florets around the outside, and the disk in the center. The drawing on the far right shows a cross section of the disk, with opened disk florets near the outside of the circle, and unopened disk flowers near the center. I gather, and I may be wrong, wrong, wrong, that in a case like the one illustrated, the ray florets are sterile, while the disk florets are fertile.

Pityopsis graminifolia
"Narrow leaf Silk Grass"

To make things more complicated, some members of the Aster family have only ray flowers. In this case they are fertile, and they are called ligulate florets. Ligulate florets have teeth. In the drawing of Hieracium megacephalon, "Hawkweed," below, there is no central disk, only ligulate florets. The sexual parts of the florets emerge from the base, so are clustered in the center of the head. Notice the teeth.

Hieracium megacephalon
Coastal Plain Hawkweed

And, there are members of the family with only disk florets, like Emilia, Ageratum, or thistles.

Circium, sp. "Thistle"

I find the seemingly infinite variety of ways in which plants go about their business utterly fascinating, and I keep discovering new things every time I look hard even at familiar plants.