Needle and thread, Hesperostipa comata, is a native, long-lived perennial, cool season, mid grass, monocot, of the grass family that is abundant on healthy mixed grass prairie plant communities. Needle and thread can grow on sandy, shallow, silty, overflow, clay, and thin claypan ecological sites. Needle and thread is drought resistant. Tillers live for two growing seasons; the first growing season as a vegetative tiller and the second season as a reproductive lead tiller.  

Lead tiller early season activity starts by regreening of active chlorophyll on portions of the carryover leaves that have intact cell walls from the previous growing season vegetative tillers. These green portions of the carryover leaves provide large quantities of carbohydrates and the energy needed for production of new leaves. New leaf growth starts slowly in early and mid April, the growth rate increases during May and June, and then becomes much slower during July. Tillers develop new leaves rapidly during May and consistently produce 3.5 new leaves by 1 June, except the first and second leaves will be missing, or sometimes just the broken stubs remain. Lead tillers at the technical 3.5 new leaf stage (with the first two leaves missing) are physiologically capable of positive response to partial defoliation of 25% to 33% of the leaf weight by graminivores. The tallest basal leaf is at 73.0% of height on 1 June and the lead tillers contain 15.2% crude protein and 0.265% phosphorus during early June. Early flower stalk growth shows swelling around mid May reaching the boot stage by late May, progressing rapidly through head emergence, and reaching the four week flower stage period during early to late June. Basal leaf and stalk growth in height is rapid during June. Flowering lead tillers have 1 or 2 very small stalk leaves and have usually produced 2 to 7 basal leaves. No new leaves are produced after the anthesis stage. Basal leaves reach 97.0% of height, seed stalks reach 84.7% of height, and lead tillers contain 12.0% crude protein at the end of June. Basal leaves and seed stalks reach maximum height and the lead tillers drop below the crude protein requirements of lactating cows during the first week of July. Seeds develop through the milk and dough stages during late June to mid July, with most seeds reaching maturity during late July and some seeds are shed with some seeds held on the stalk during late summer. 

Vegetative tillers are derived from carryover tillers that were fall tillers from the previous growing season and some are derived from early season initiated tillers. Vegetative tillers have slightly slower growth rates than reproductive lead tillers during the early portion of the growing season because they were derived from less developed originating tillers and they had weak inhibiting hormones. Most vegetative tillers produced 3.5 new leaves shortly after the lead tillers and became independent after producing the full fourth new leaf. When the lead tiller growth rates decreased greatly during the high nutrient demand from seed stalk development during July, the independent vegetative tiller growth rates did not slow down. During the growing season, 81.6% of the vegetative tillers produced 5 leaves, 16.3% produced 6 leaves, 2.0% produced 7 leaves, 0.1% produced 8 leaves, and 0.1% produced 9 leaves. Traditional grazing management practices that are able to produce less than 100 lbs/ac of available mineral nitrogen have less than a third of the quantity of vegetative tillers as grazing management practices, like the twice-over system, that can produce greater than 100 lbs/ac available mineral nitrogen. Vegetative tillers provide around three fourths of the forage weight on the twice over system after mid July.

Secondary tillers are derived from initiated vegetative growth of axillary buds on lead tillers during the growing season. The growth rate of secondary tillers is hormonally controlled by a dominant lead tiller that has proprietary access to all essential nutrients available to the secondary tillers. As tyrannical as this may appear, this arrangement gives secondary tillers far superior survivability than an independent grass seedling. Reproductive lead tillers have a high nutrient demand during the flower stalk growth and development stages causing the lead tillers to restrict nutrient flow to the secondary tillers resulting in very slow rates of growth. Secondary tillers can remain at the 2 or 3 leaf stage for a month or two. During growing seasons with periods of water stress or other problematic conditions, the nutrient restrictions could be great enough to cause secondary tiller termination. If the secondary tillers survive through the seed development stage, the lead tiller releases greater quantities of essential nutrients to the subordinate secondary tillers. During the growing seasons of 1987 to 1989 with high water deficiency conditions, the quantity of surviving secondary tillers was 73.6% greater on the twice-over system than that on the traditional seasonlong treatment.

For more information Go To:

https://www.ndsu.edu/agriculture/ag-hub/publications/dickinson-rec-2018-annual-report