Basal Leaf

Basal Rosettes of Evening Primrose (Oenothera drummondii)
Harry Rose / Flickr / CC BY-2.0

A basal leaf is one that grows from the lowest part of the stem. Basal, in general, refers to the base of a structure. Plants with basal growth often grow in what is called "rosettes", meaning the leaves form a circle at the base of the stem, all growing to a similar length, and somewhat resembling the petals of a rose.

Why Do Some Plants Grow Basal Leaves in Rosettes?

There are several reasons for this occurrence.

The cluster of low sitting leaves can serve as protection for the roots of the plant, when the top of the plant dies back in winter.

Plants like lettuce and many succulents may grow in rosettes to conserve water. When they are ready to go to seed, the stem elongates, or bolts, and sets flowers and seeds. In this case, the original plant usually dies.

Many weeds, like the common dandelion and plantain, are protected by their basal rosettes because the leaves make it harder to pull the plant from the ground. The leaves give way, long before the root pulls lose.

What Plants Grow Basal Leaf Rosettes?

Some perennial plants form only temporary basal rosettes, for one reason or another. They eventually send up a stem with additional leaves and the basal rosette may disappear completely. These include: harebell (Campanula  rotundifolia), oxeye daisy (Chrysanthemum  leucanthemum), whorled stonecrop (Sedum  ternatum), and Yarrow (Achillea  millefolium),

However some plants, like the English daisy (Bellis  perennis),  maintain their basal rosette shape through their entire life cycle. These  are called "perpetual rosette plants". The flower stems simply grow above the rosette.

Then there are perennial plants that send up new basal foliage once the older foliage starts to look tired and worn.

This new growth forms a rosette, such as the new foliage that emerges at the base of lungwort (Pulmanaria) plants, once the flowers begin to fade. When this happens, the older, fading leaves should be trimmed off, leaving just the basal rosette and allowing the plant to concentrate on storing its energy and food, while it prepares for next season. Other examples of perennials that send up new basal growth later in the growing season are: coral bells (Heuchera), Jacob's ladder (Polemonium), true geraniums, and dandelions.

Annual plants can also grow as rosettes. Many of them are weeds, like the dandelions and plantain mentioned earlier, but there are also some annual garden plants including: English daisy (Bellis  perennis), fleabane (Erigeron  annuus), and viper's bugloss (Echium  vulgare).

Many rosette forming plants are biennials, which makes sense since biennial plants spend their first year soaking in nutrients and storing energy. They don't need long stems and lots of foliage competing with their roots. So it's not uncommon for biennials, such as foxgloves (Digitalis), to grow as basal rosettes their first year, conserving their energy, and then sending up a regular flowering stem in their second year of growth.

Some biennials that form rosettes in their first year include: black-eyed Susan (Rudbeckia  hirta),  lobelia, rose campion (Lychnis  coronaria), Ranunculus, and wand flower (Gaura)

Although there is a lot of variety among plants that form basal rosettes, plants that maintain their rosettes tend to look tidy all season, since their resources are so focused in their minimal growth.