Buddleja simplex is probably extinct, as no record of it has been made for nearly 200 years. It was a species endemic to Saltillo

Saltillo

Saltillo is the capital city of the northeastern Mexican state of Coahuila and the municipal seat of the municipality of the same name. The city is located about 400 km south of the U.S. state of Texas, and 90 km west of Monterrey, Nuevo León....

 in Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, described and named by Kraenzlin

Friedrich Wilhelm Ludwig Kraenzlin

Friedrich Wilhelm Ludwig Kränzlin In the history of the European study of South African orchids, Fritz Kränzlin appears after Heinrich Gustav Reichenbach describing many new orchids in the region, and revising some of the genera...

 in 1912.

Description

B. simplex is a small shrub, the young branches subquadrangular with adpressed tomentum

Tomentum

Tomentum may refer to the following:*In botany, a covering of closely matted or fine hairs on plant leaves. *A network of minute blood vessels in the brain.* Tomentum in zoology are a short, soft pubescence...

. The small, membranaceous oblong-elliptic

Leaf shape

In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...

 or oblong-lanceolate

Leaf shape

In botany, leaf shape is characterised with the following terms :* Acicular : Slender and pointed, needle-like* Acuminate : Tapering to a long point...

 leaves have 0.5 - 1.5 cm petioles, and are 2 - 4 cm long by 0.5 - 1.2 cm wide, tomentulose

Tomentum

Tomentum may refer to the following:*In botany, a covering of closely matted or fine hairs on plant leaves. *A network of minute blood vessels in the brain.* Tomentum in zoology are a short, soft pubescence...

 above, tomentose

Tomentose

Tomentose is a term used to describe plant hairs that are flattened and matted, forming a woolly coating known as tomentum. Often the hairs are silver or gray-colored...

 below. The bracted

Inflorescence

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

 inflorescences are 5 - 10 cm long, comprising 8 - 10 pairs of sessile

Sessility (botany)

In botany, sessility is a characteristic of plants whose flowers or leaves are borne directly from the stem or peduncle, and thus lack a petiole or pedicel...

 or pedunculate

Peduncle (botany)

In botany, a peduncle is a stem supporting an inflorescence, or after fecundation, an infructescence.The peduncle is a stem, usually green and without leaves, though sometimes colored or supporting small leaves...

heads < 0.6 cm in diameter.

The species is considered very close to B. sessiliflora, the latter having marginally larger flower heads and longer fruits.