Black Cohosh Seed Germination and Conservation W

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2018 Black Cohosh Seed Germination and Conservation W. John Hayden University of Richmond, [email protected]

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Recommended Citation Hayden, W. John. “Black Cohosh Seed Germination and Conservation.” Sempervirens Winter 2017/2018: 6-7.

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Article and illustrations by W. John Hayden, Botany Chair

ike many plant enthusiasts, I have the natural progression of seasons. but epicotyls remained inactive spent a considerable amount of Seeds that mature and disperse in late until mid-March. Seeds of Hepatica time planting seeds. Every year I summer or fall will be exposed, fi rst (Anemone acutiloba ), also studied grow many vegetables—my garden to warmth and moisture, and then to by Baskin and Baskin (1985), show a always includes some annual bedding the cold temperatures of winter, before similar pattern. plants—and I sow seeds of cover germinating in the warmth of spring. Baskin and Baskin (1985) offered crops (winter wheat, winter rye, and The savvy native plant gardener several hypotheses for the adaptive buckwheat) by the tens of thousands. employs a process called stratifi cation value of epicotyl dormancy observed While I have committed vast numbers to mimic this natural cycle; seeds sown in Black Cohosh and Hepatica. For of propagules to moist soil, I cannot in moist soil, or merely wrapped in example, cotyledons that remain say that I have watched every single moist paper towels, are given a winter- inside the seed may suffer less one sprout. Nevertheless, I certainly like cold treatment in order to prompt predation than would be the case if have observed the germination germination when brought back to these young and tender tissues were process many, many times for lots warmth. exposed all winter long. Further, of different seeds. For these seeds of Actaea racemosa (Black Cohosh), retention in the seed may ameliorate garden plants, germination is quite our 2017 VNPS Wildfl ower of the extreme fl uctuations in winter rapid, just a few days to maybe as Year, exhibits an interesting twist temperatures experienced by the much as two weeks, tops—provided on the usual cold stratifi cation epicotyl meristem. Finally, the Baskins that temperature and moisture are requirement: within each seed, the noted that precocious development appropriate. Further, in the usual radicle and epicotyl have different of a root system could help provide case, the embryonic root (radicle) requirements for breaking dormancy. water and mineral nutrients for the emerges fi rst, followed in short order In nature, Black Cohosh seeds epicotyl in spring better than if both by embryonic leaves (cotyledons) and (Figure 1) mature and disperse while root and shoot were developing the fi rst bits of the seedling shoot temperatures are still reasonably simultaneously. (epicotyl). Sometimes, as in Garden warm. Sooner or later the seeds will It occurs to me that there Peas, the cotyledons stay below be moistened by autumnal rains, and may be another perspective on ground, but the pattern of radicle the germination process commences precocious radicle and delayed shortly before epicotyl is still the with emergence of the radicle. The epicotyl germination in Actaea and typical situation. epicotyl, however, at this time, Anemone . Both of these plants are In contrast, anyone who has grown remains dormant. Time passes, fall members of Ranunculaceae, a family temperate zone trees, shrubs, or becomes winter, and winter brings in which seeds characteristically wildfl owers from seed knows that our cold temperatures that provide the have “underdeveloped” embryos. wild native plants do not always follow necessary “stratifi cation” effect “Underdeveloped,” of course, the quick and straightforward pattern required by the epicotyl. is in comparison with seeds of described above for domesticated When warm spring temperatures other plants. Figure 2 shows a plants. Often, germination of native return, the epicotyl becomes active Black Cohosh seed that has been plant seeds can be a protracted process and emerges, establishing the shoot sectioned longitudinally with a razor requiring months of patient waiting. system of a Black Cohosh seedling. blade. Most of the seed consists of Further, our native species may require Baskin and Baskin (1985) studied endosperm cells full of stored food a particular sequence of moisture seed germination in Black Cohosh. for use by the embryo. The embryo and temperature exposure before For seeds sown in late September of this fully mature seed is the dormancy breaks and germination and exposed to ambient temperature remarkably small heart-shaped blob begins. Usually, native species time conditions of Lexington, Kentucky, near the narrow end of the seed, the the germination processes to match radicles emerged in early November, size and shape of which is much like a Sempervirens , Winter 2017-2018 7

textbook example of an early embryo germination to determine whether shortly after fertilization of the egg. epicotyls are truly winter dormant or In other plant families, seeds generally whether they are opportunistically have much larger embryos at maturity. active, following a cryptic post Castor Bean ( Ricinus communis ) dispersal developmental process (Figure 3) provides a convenient and getting ready for eventual example; though endosperm volume germination in spring. is still greater than that of the Why do the details of Black embryo, cotyledons of Castor Bean Cohosh seed germination matter? embryos are well-developed, and the As pointed out by Kaur et al. (2013),

whole embryo extends for nearly the growing popularity of Black

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* the full length of the seed. Perhaps Cohosh in herbal medicine threatens

: h = i ` W ` Y ` = W B A @ ` 1 3 epicotyls of Actaea racemosa have unsustainable overharvesting of delayed emergence from the seed wild populations for its roots and because they are anatomically and rhizomes. Cultivation of Black physiologically too immature to Cohosh could alleviate pressure germinate when the seeds disperse in on wild populations; thus, efﬁ cient autumn. I wonder if the cotyledons propagation by seed could be and epicotyls of Black Cohosh are an important step to make that truly dormant and inactive during conservation-worthy goal a reality. v

winter. Might they continue to

! " # $ % & ' ( ) develop through the winter, whenever temperatures are warm enough to Baskin, J.M., and C. C. Baskin. permit growth? There certainly is 1985. Epicotyl dormancy in seeds ample food stored in the endosperm, of Cimicifuga racemosa and

and the precociously developed root

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would be able to supply water and

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W Botanical Club 112: 253-257.

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Kaur, B., J. McCoy, and E. Eisen-

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/ / 9 E 3 5 7 + 8 : 3 3 9 L 8 7 3 . + 6 , / 6 9 3 8 G / . 4 1 8 stein. 2013. Efﬁ cient, season-inde- are developmentally competent pendent seed germination in Black to emerge. It should be a simple Cohosh ( Actaea racemosa L.). matter to monitor Black Cohosh Amer. J. Plant Sciences 4: 77-83.

seed structure over the full course of

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