The Mahatma, Morya from Agni Yoga in the '20's:
Certain plants exist as reservoirs of prana. The pine trees collect it as if in electric needles. And as a bond between heaven and the depths of earth, the earth is covered with living antennae which gather and preserve the true renewing element of the spiritual tissue. Leaves of Morya's Garden - Book 2 - Illumination (1925)
When it is not the season for flowers, it is useful to have small pine trees. Like a dynamo they accumulate vitality, and they are more effectual than right breathing. Instead of by ritual breathings one can thus receive a most condensed supply of prana. Of course, a state of rest also increases the action. Leaves of Morya's Garden - Book 2
True, true, true - people must settle themselves in tested localities. Even a bear shows greater care in selecting his den. Plants will indicate the better possibilities. Look for cedars and pines, heather and oak, grass and flowers of vivid color. Natural electrification in a locality is necessary. Large, long needles of evergreen are the best condensers of electricity. Heights above eleven thousand feet, devoid of vegetation, provide useful prana. New Era Community (1926) - 182