Primula strumosa vs Primula sikkimensis

Being able to identify a species in the field is like being able to recognize a friend in a crowd. The more familiar you are with your friend’s features, the easier it is to find him. If you aren’t sure of a particular species, botanical keys can help you determine an identity, but that requires you to be familiar with some technical botanical terms.

When I was recently asked to distinguish between P. strumosa and P. sikkimensis, my answer included technical terms which not everyone was familiar with. Part of my reasons for starting the website “Primula World – A Visual Reference for the Genus Primula” at www.primulaworld.com was to be able to show the important characteristics of species and their variations through images.

Primula sikkimensis

Primula strumosa

Primula strumosa and Primula sikkimensis are both yellow flowered species found in a large area of the Himalaya including Nepal. They belong to different Sections (groupings) in the Genus, with P. sikkimensis being in Section Sikkimensis and P. strumosa being in Section Petiolares. Species in each Section are grouped according to common characteristics.

Though both of these species have yellow flowers, the structure of those flowers is different. P. sikkimensis has campanulate (bell shaped) flowers, and the calyx (the cup shaped structure at the base of the flower) is split to the middle into sharp triangular teeth (indicated by the red arrow). P. strumosa has flat faced flowers with a calyx split to the middle but into blunt (rounded) teeth (indicated by the red arrow).


Primula sikkimensis flowers

Primula strumosa flowers

 The leaves of these two species are also different. P. sikkimensis has leaves which are of a thin, papery texture and usually has a fairly distinct petiole (leaf stalk) whereas P. strumosa has leathery leaves with a broadly winged petiole (that is, no distinct leaf stalk).

Primula sikkimensis leaf

Primula strumosa leaf

Primula strumosa overwinters above ground as a resting bud. This resting bud is covered in yellow farina (a powdery substance) and the bud scales remain around the base of the plant, under the true leaves. Primula sikkimensis is deciduous and disappears completely below ground until Spring therefor it has no bud scales.

Primula strumosa resting bud

Most Primula species have seed capsules which split into 5 parts and empty from the top of the capsule. Members of Section Petiolares have a different capsule where a thin membrane covers the seeds which eventually disintegrates, releasing the seeds.

Primula sikkimensis seed capsule

Primula strumosa seed capsule