Lupines, belonging to the genus Lupinus, are members of the Fabaceae family, valued by gardeners for their characteristic tall, spire-like flowers. Identifying these plants in their earliest life stage, before they develop mature foliage, can be a challenge for those attempting to distinguish them from common weeds. The appearance of the first leaves, which differ structurally from the mature foliage, is the initial step in confirming a lupine seedling. Paying close attention to the size and shape of these first leaves, and then the subsequent true leaves, allows a gardener to accurately identify the young plant.
The Initial Appearance: Cotyledon Leaves
The first structures to emerge from the soil after germination are not true leaves but cotyledons, which serve as temporary food storage organs for the developing seedling. Lupine cotyledons are notably thick and fleshy, reflecting the substantial energy reserve provided by the large lupine seed. They are often described as bean-shaped or spatulate, meaning they are oval with a slightly tapered base. These cotyledons are significantly larger than the cotyledons of many other garden plants.
These initial leaves typically measure between 15 and 25 millimeters from tip to tip, presenting as a pair of simple, dark green structures. The cotyledons emerge on a stem that is sometimes tinged with a reddish or purplish color. Because the cotyledons are simple and unlobed, they offer little unique identifying information for the genus, making close observation of the next stage necessary.
Confirmation Stage: True Leaf Characteristics
The definitive characteristic that confirms a plant is a lupine seedling is the formation of its true leaves, which appear shortly after the cotyledons have fully expanded. These leaves are palmate, meaning they are structured like the palm of a hand with leaflets radiating from a single central point. This palmate arrangement is highly distinctive and is the primary feature separating lupines from most other seedlings.
The true leaves of a young lupine typically consist of five to 11 individual leaflets. Each leaflet is elongated and lance-shaped, generally displaying a vibrant green coloration. The surface of the leaves is often covered in fine, minute hairs, which can give the foliage a slightly grayish-green or soft, fuzzy texture. These true leaves are arranged alternately along the developing stem, creating a whorled effect as they grow larger and more numerous.
Avoiding Misidentification: Lupines vs. Common Seedlings
The initial, simple shape of the lupine cotyledons can lead to confusion with other members of the Fabaceae family, such as pea or bean seedlings, which also emerge with fleshy, bean-shaped first leaves. However, the large size and notably thick texture of the lupine cotyledons can help differentiate them from the thinner cotyledons of many common annual weeds. A key practical measure for identification is waiting for the next set of leaves to develop.
The vast majority of common garden weeds and simple-leaved plants will not produce the highly specialized palmate true leaves characteristic of the Lupinus genus. If a seedling displays simple, oval cotyledons followed by the emergence of a leaf with multiple leaflets radiating from a single stem point, it is almost certainly a lupine. This unique leaf architecture serves as a reliable marker, allowing gardeners to confidently distinguish desirable lupine seedlings from unwanted volunteer plants.