Asperula aristata subsp. scabra is a mat-forming alpine rockery plant in the Rubiaceae with a low, spreading habit. It carries foliage that can be evergreen or deciduous and flowers from May to July. The plant is native to continental Portugal. It is suited to tight, well-drained situations such as crevices and gravel pockets.

A mat-forming alpine rockery plant from Portugal that flowers May to July and suits gravel, crevices, containers and garden edging.

Cynanchica, commonly known as woodruff, is a genus of flowering plants in the family Rubiaceae. It contains 73 species and has a wide distribution area from Europe, northern Africa, the Middle East and central Asia.

Asperula aristata subsp. scabra

Woodruff | Asperula aristata subsp. scabra

Crucianella stylosa is a perennial in the Rubiaceae (madder) family valued for its aromatic foliage. It is grown primarily as a ground cover or in rock gardens where its summer flowering provides colour. Flowers appear from June to August. It prefers full sun to partial shade on well-drained soil with moderate moisture.

Caucasian crosswort (Crucianella stylosa) is an aromatic perennial ground cover for sun or part shade, flowering June to August.

https://en.wikipedia.org/wiki/Phuopsis_stylosa

Phuopsis is a genus of flowering plants belonging to the family Rubiaceae.

Crucianella stylosa

Caucasian crosswort | Crucianella stylosa

Guettarda speciosa is an evergreen shrub or small tree in the Rubiaceae, noted for large, prominently veined leaves and summer-flowering heads. It prefers full sun on a well-drained neutral loam in a sheltered, south-facing position. Flowering occurs July to September. Hardiness is H4, so it performs best in milder, protected UK sites.

East Indian Zebra Wood (Guettarda speciosa) is an evergreen coastal shrub with summer flowers from July to September.

Guettarda is a plant genus in the family Rubiaceae. Most of these plants are known by the common name velvetseed.

Guettarda speciosa

East Indian zebra wood | Guettarda speciosa

Richardia elliottiana is a species in the Rubiaceae, placed in the genus Richardia — a group commonly called Mexican-clover. The genus is mainly composed of annual plants native to tropical and warm-temperate parts of the Americas. In the UK it provides a summer display, with flowering from July to September. Cultivation tends to follow the seasonal pattern of other warm-origin annuals.

Richardia elliottiana (Mexican-clover) is a Rubiaceae species that flowers from July to September and is grown for summer display.

Richardia (Mexican-clover) is a genus of about fifteen species of flowering plants in the family Rubiaceae. They are native to tropical to warm, temperate regions of the Americas, with one species also native to Fiji.