142 MISSOURI BOTANICAL GARDEN BULLETIN 
All perennials immediately after flowering enter into a semi- 
dormant or resting period, in the case of the iris, consider- 
able root growth being made at that time. If transplanted 
at the beginning of this period, in two weeks or a month 
they will have completely established their root systems in 
the new soil. Some of the early flowering plants, if cut back 
to the ground immediately after flowering, put out new top 
growth and bloom again before fall. 
It should always be remembered that plants that are com- 
ing into flower are putting forth their best efforts toward 
perfect flowers, and eventually perfect seed, and a large 
amount of nourishment is required. Watering of perennials 
should therefore be attended to regularly until they have 
bloomed, but after blooming, during the period of rest, very 
little, if any, water is required. 
The following list does not include all of the perennials 
that may be grown in St. Louis, but it does include a large 
number of those that are most easily cultivated and that are 
productive of the best results. From this list all early flower- 
ing bulbs, such as tulips, narcissus, hyacinths, etc., have been 
omitted. 
Achillea.—This valuable perennial, commonly known as 
the milfoil or yarrow, is easily grown and thrives well in 
St. Louis. The different species vary both in habit and 
in color of flowers and by a proper selection of them, the 
plant may be had in bloom from ay until October. Achil- 
lea Eupatorium, E. filipendulina, and A. tomentosi are 
ellow-flowered varieties that are respectively 4, 3, and 1 foot 
igh, and bloom from June to August. A. Millefolium, 
“Cerise Queen,” and A. Millefolium roseum are rose-colored 
varieties, 2 to 3 feet high, which bloom during midsummer. 
The prettiest of the milfoils and the most desirable for 
hci use are the varieties of A. Ptarmica, namely, “The 
earl” and “Boule de Neige,” both of which produce masses 
of small white flowers very unlike the other milfoils, the 
former being a single variety and the latter double. They 
are also desirable because of their low habit, being from 1 
to 2 feet high. 
Alyssum.—Alyssum saxatile compactum and A. saxatile 
flore pleno are low-growing, yellow-flowered perennials that 
bloom in early spring—a time when yellow is rather uncom- 
mon in St. Louis gardens. They have grayish foliage and 
make an attractive border plant during the summer. 
_ Anchusa italica—The common name for this species 
is the alkanet. It is a plant of rapid growth requiring 
considerable room for full development. As is true of 
