Rosette

Bull Thistle (Cirsium vulgare)

Asteraceae - Daisy family

A taprooted biennial or monocarpic perennial from Europe, Asia, and Africa. It has been introduced to at least the United States and is considered a noxious or injurious weed in many countries. The thorns can pierce gloves. A close relative of Cardoon (Cynara cardunculus), the leaf stalks are likewise cooked and eaten, though I have never tried it.

Common Mullein (Verbascum thapsus)

Scrophulariaceae - Figwort family

This is a biennial native to North Africa, Asia, and Europe. It has been naturalized in the US and is a common roadside weed. This one is a second year 'adult' that will likely flower this year. Last year I allowed one to grow in my garden, it reached a towering 12'! The flowers were worked by bees in the early morning in summer for both nectar and pollen. The thick hairy leaves give it the flattering common name: Cowboy toilet paper. No, I haven't tried it.

Verbascum thapsus, a young first yearling.

English Plantain (Plantago lanceolata)

Plantaginaceae - Plantain family

Not in any way related to the cooking plantain (Musa sp.), English Plantain is another naturalized weed from Europe. The root and leaves are used medicinally, and the flowers are suggested as being good for beneficial insects, though I have seen no such interest.

Viper's bugloss (Echium vulgare)
Boraginaceae - Borage family
A showy blue flowered herb I grew from seed. Touted as the best bee plant on earth due to the extremely productive nectaries and trichomes (hair-like structures) in the flower tube protecting the nectar from rain or evaporation.

Italian bugloss (Anchusa azurea)
Boraginaceae - Borage family
Seed grown plants, similar to Myosotis but larger in all aspects.

Wooly lambs ears (Stachys byzantina)

Lamiaceae - Mint family

An easy deer resistant non-aromatic mint relative that spreads large clumps over time with the aid of adventitious roots. The flower spikes are hairy and covered in purple florets. This plant is very tolerant of drought, and of almost any soil that isn't waterlogged.

________________________

The reason I have brought all these plants together is to show you the 'rosette' leaf structure that is common among many plant families. Not pictured, but also sharing this leaf form are plants in the families Asteraceae, Crassulaceae, Papaveraceae, and Saxifragaceae, among others and genera such as Agave, Lactuca, Papaver, Saxifraga, Sempervivum, Senecio, Taraxacum, and countless others. The rosette offers plants protection from a variety of possibly harmful influences.

The center of the rosette often conceals the sensitive growth point from adverse weather, cold temperatures, and insects. A multitude of fine hairs, another theme of these photos, also aids the plants by insulating them, as well as possibly averting attack by insects when the hairs are dense enough. The hairs also help to conserve moisture in the heat of summer, slowing the effect of evaporation from wind and sun as well as catching moisture from morning fog. 

Some of the rosette forming plants, such as Verbascum thapsus, form rosettes that are quite large in diameter. The size of the outermost, oldest leaves helps to keep competition low by disallowing encroachment of nearby competing plants. The leaves also help retain soil moisture content and probably help to insulate the root crown to some extent.

I'm sure there are other benefits to the rosette leaf structure that I haven't thought of, but I encourage you to look at the ground and see if you can identify any such structure for yourself. You will see that this is extremely common, particularly for weedy non-native plants in lawns, roadsides, and empty lots. Plant life is resilient, and ingenious form results in superior success.

________________________