Abstract: Dahlia Cav. is a beautifully flowering perennial plant from the family Asteraceae Dum. It has storing root tubers that do not survive during the winter in the open ground of central Russia. This crop is characterized by a high variety of colors, shapes and sizes of inflorescences, different plant heights, long-term stable decorative effect from the beginning to the end of the growing season. The purpose of the study is to analyze the Dahlia × cultorum collection in the Botanical Garden-Institute of the Volga State University of Technology (Yoshkar-Ola, Mari El Republic). As of 2021, plants of 32 cultivars were grown in the exposition «Ornamental Herbaceous Plants», each cultivar is represented by 1-5 plants. It is established that the available cultivars belong to 6 classes according to the structure of inflorescences, the largest number of them belong to the class of Decorative and Semi-Cactus (12 and 8 names, respectively). According to the color of the inflorescences, the largest number of cultivars has bicolor inflorescences. The small-flowered cultivars dominated according to the inflorescences size. In general, most cultivars with large and medium-sized inflorescences have a decrease in their size. We can replenish the collection with varieties from the smallest represented classes, as well as the missing 6 classes. The results can be used in the practice of settlements landscaping of the Mari El Republic and nearby regions.

Abstract: Crocuses are beautifully flowering corm-bearing plants. They begin the growing season immediately after the snow melts. The research contains the results of phenological observations of 2014-2019 for plants of 6 Crocus taxa in the conditions of the Mari El Republic. Cultivars with early, medium and late periods of phenophase passage were identified. A flowering phenospectrum of the studied crocuses has been compiled. Crocuses vegetate from mid-April to early June for 40-50 days, and bloom from the third decade of April to early May. C. chrysanthus 'Prince Cloues' is characterized by the earliest unfolding of leaves and a short duration of their growth. The greatest value for landscaping is C. versicolor, characterized by the longest growing season and the earliest flowering, as well as C. chrysanthus ' Romance’ and C. angustifolia, characterized by the longest flowering within 2 weeks. The flowering of C. sieberi 'Spring Beauty’ is unstable. The obtained data on the seasonal development of crocuses can be used when including them in rockeries, alpine slides and other flower beds in natural-style gardens.

Abstract: Daylily (Hemerocallis) is a perennial herbaceous plant widely used in landscape gardening. Daylilies are prized for their long term flowering mainly in late summer and low maintenance cultivation. According to flower spike height, the varieties are divided into runt, medium-growing and tall. The article contains the results of the study of 21 medium-growing daylily varieties’ terms of flowering in the botanic garden of the Volga region State University of Technology (Yoshkar-Ola, the Republic of Mari El). The research was conducted in 2015 - 2017. The calendar dates were converted into a continuous series. All varieties were classified as early, medium or late according to the terms of the beginning and the end of flowering and its duration. During three years of research, the earliest beginning of the phenological phase was registered in 2016, and the latest one  - in 2017. The early beginning and ending of flowering were typical for the varieties “Dr Regel” and “Royal Sovereign”. The late beginning of flowering was registered for the “Country Club” variety, and the late ending - for “Sandalwood”. Other varieties were classified as medium-term. The varieties “Royal Sovereign”, “Tejas”, and “Sugar Candy” are characterized by a short flowering period, while “Sandalwood” and “Derby Bound” - with a long one. It was established that the late-flowering varieties are characterized with a longer flowering period.