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  • Bumald’s Bladdernut – The Cauliflower Tree

    My first exposure to Staphylea bumalda, a species of Asian bladdernut shrub, was this ethnobotanical survey of wild food plants utilized in a rural mountain village in central China. The so-called “Bumald’s bladdernut” caught my attention because it was not only one of the most commonly eaten wild vegetables there, but also the most popular wild vegetable served in restaurants. Bumald’s bladdernut leaves were more popular in restaurants than the leaves of the Chinese toon tree,Toona sinensis, which are delicious and a revered wild food in China. The study features photos of bladdernut leaves being served as a vegetable side dish and dried in the sun for long-term storage.

    The survey area in central China where this story begins.

    What exactly was this plant which was apparently so delicious? After consulting several botanical references, I learned that Staphylea bumalda is a 6 foot (1.8 m) tall multi-stemmed shrub with attractive white flowers in the spring. It has a wide distribution in East Asia which includes China, Korea and Japan. The characteristic feature of the bladdernuts in the genus Staphylea is their inflated seedpod (bladder) which contains small hard seeds (nuts). Being a bladdernut, Staphylea bumalda is closely related to the American bladdernut Staphylea trifolia and the European bladdernut Staphylea pinnata, but differs from these other species in its smaller overall size. The plant can be grown in sun or shade in moist soils down to at least USDA zone 5.

    The flowers of Staphylea bumalda as photographed by iNaturalist user Rob Macfie in South Korea.

    The Chinese name for the plant listed in the aforementioned study is 树花菜, pronounced shù huācài – which translates to “tree cauliflower”. This name conjures fantastical images of its edible usage – who wouldn’t want to grow a cauliflower tree? The name refers to the small clusters of white flower buds which are harvested and eaten alongside the leaves in the spring. These flowerbud clusters are only a few inches long, but do resemble a tiny cauliflower or broccoli raab, despite being unrelated to either. The leaves and flowerbuds are generally eaten cooked, and can be used in a variety of cooked dishes.

    You can see why they call it “tree cauliflower” in this photo by iNaturalist user onidiras.

    In my opinion what sets this plant apart from others is the incredible flavor of the leaves and tiny “cauliflowers”. The plant has a strong flavor of sesame, as if the leaves were dipped in toasted sesame oil with a dash of black pepper. When I tried the leaves and flower buds for the first time I was very impressed by their flavor and chewy texture. I’ve tasted many unusual plants over the years and often they’re not terribly good. This was one I could easily eat a whole bowl of! On an established shrub the yield of edible leaves and “cauliflowers” can be tremendous. As referenced in the Chinese study, the leaves are also easily preserved by drying.

    A plate of young leaves and cauliflowers of Staphylea bumalda just after harvesting.

    When I consulted my Korean and Japanese foraging books I also found glowing reviews for the flavor: “The soft leaves have a refined taste without any bitter or peculiar flavor and are popular with people of all ages, from children to the elderly.” – high praise from a book that frequently recommends boiling plants multiple times to remove bitterness! I would later learn that a small industry is forming around the plant in rural China. Rural farmers are growing it in large numbers to sell to local restaurants and to export to cities. Because it is harvested in the spring before most crops are ready, it gives farmers a big financial boost going into the growing season. The recent surge in interest in wild foods and traditional Chinese medicine has only made it more successful. Unfortunately the best article I found on the subject has since been removed by its Chinese publisher.

    Boiled bladdernut leaves and flower buds with soy sauce for dipping.

    My first time seeing one of these plants in person was in August of 2021 during a trip to the Polly Hill Arboretum on Martha’s Vineyard. Staphylea bumalda is an uncommon species in cultivation, but as luck would have it, the proprietors of the arboretum had collected seed of it during a 2007 expedition to Japan. The 14-year-old plants I witnessed had a similar habit and silver-gray bark as a serviceberry, (Amelanchier species) but with leaves in threes and copious seed pods hanging on each bush.

    While most bladdernuts have a more cylindrical “bladder” with 3 or more segments, Staphylea bumalda has a flattened bladder with 2 lobes. This unique characteristic makes it easy to tell that you’ve got the right species. Each side of the bladder contains between 1 and 3 seeds about the size of a lentil – much smaller than the nuts of the American and European species. While the nuts of the larger bladdernuts can be shelled and eaten, the nuts of Staphylea bumalda are far too small to be used for this purpose, though there is some evidence that they have been pressed for oil in China.

    Staphylea bumalda “bladders” (center) and “nuts” (top left).

    I collected a large number of seeds from the bushes at the Polly Hill Arboretum during my visit, and upon returning home I attempted to germinate them. As it turns out, most bladdernut species are very difficult to grow from seed. Each individual seed has a hard and impermeable seed coat which inhibits germination. While the larger bladdernuts can be cracked or filed to open up the seed coat, Staphylea bumalda seeds are so small that attempting to crack or file them often results in the seeds being crushed. I failed in my first year trying to grow them, and so returned to the Polly Hill Arboretum the following year to collect more. Only after pretreating the seeds with concentrated sulfuric acid did I find some success.

    Success! Baby Staphylea bumalda plants.

    Out of the roughly 200 seeds that I collected, I only succeeded in getting exactly 2 to germinate! I wanted to grow at least 2 plants so that they could cross-pollinate, allowing me to one day collect seeds from my own garden. As you can imagine, I have since been protecting both plants with every ounce of my horticultural knowledge. I would say that they’re easily the most babied plants in my landscape! If you’re looking for seeds to try for yourself, there’s no longer any need to visit an obscure arboretum or botanical garden. Seeds are available online from Sheffield’s Seed and occasionally on eBay. I’ve ordered them from both sources and can at least confirm that they’re selling the right species, though I expect germination to be difficult from any source!

    After reading all of this, some of you may be wondering about the edible uses of the many other bladdernut species. In my opinion the young leaves of any Staphylea is worth trying. The study mentioned at the start of this article also lists Staphylea holocarpa, another Chinese species, as edible – though much less commonly used than S. bumalda. Staphylea holocarpa ‘Rosea’ is a noteworthy cultivar of this species with beautiful pink flowers. I’m growing it in my own garden but haven’t tasted it yet. Staphylea holocarpa grows much taller than Staphylea bumalda, so it may need to be pruned to keep the leaves within reach.

    The pink-tinged flowers of Staphylea holocarpa ‘Rosea’ are edible but perhaps too beautiful to eat!

    The European bladdernut Staphylea pinnata and the Caucasian bladdernut Staphylea colchica can likely both be used in all the same ways, though I have less experience with them. I know the flowers are eaten pickled in some European countries. Staphylea pinnata has the distinction of having the largest nuts of any bladdernut species, though they’re still quite small and difficult to crack. Martin Crawford at the Agroforestry Research Trust has written about cracking and eating them. The nutmeat within the shell is green, similar to a pistachio. One other oddball in the bladdernut family is Euscaphis japonica, the Korean sweetheart tree, a larger and less-hardy species famous for its attractive red seed pods in the fall. I’ve sampled the young leaves of this species, which are listed as edible in many reputable sources, but found them tough and undesirable.

    Curiously, I’ve been unable to find any ethnobotanical record of the American bladdernut, Staphylea trifolia, being eaten. Despite its large range throughout the eastern United States, it doesn’t seem that it was utilized much by Native Americans. The species is also not listed in any of the comprehensive American foraging books in my collection. For this reason I’ve taken it upon myself to taste test the young leaves and flowerbuds. When I tried them boiled I found them to be mild and agreeable but missing the delicious sesame flavor found in Staphylea bumalda. I’ve since eaten a large quantity of the leaves with no ill effects and met others who have tried them too. I would encourage anyone curious to give them a shot. Staphylea trifolia deserves to be more widely planted anyway – it’s a highly adaptable species with attractive flowers and curious striped bark.

    I hope you’ve enjoyed this deep dive into the relatively unexplored culinary properties of the bladdernuts. I’m hoping that more people will learn about the incredible edible uses of these plants, and I’d especially like to see them become more widely available in the nursery trade. Let me know if you’ve tried them and what you think! Here’s to bountiful harvests of tree cauliflower!

    A specimen of Staphylea bumalda growing at the Cornell Botanic Gardens in Ithaca, NY.

  • The Uncommon Spicebush

    The very first plant I learned to forage was the common spicebush, Lindera benzoin. My foraging teacher “Wildman” Steve Brill pointed out the bush and explained to us that it could be easily identified by the lenticels on its bark and the fragrance it emits when a branch is broken. He recommended collecting the berries in the fall to use as a potent spice. Since that time I’ve been collecting spicebush berries every fall. My favorite way to use them is to blend one or two berries into a smoothie for a spicy kick. I think the flavor is more akin to nutmeg, cardamom, or allspice than anything else.

    Spicebush berries on the bush.

    One common mistake people make with spicebush berries is attempting to store them dried. The spicebush berry is high in fat, so it should be stored frozen to prevent the fats from turning rancid. Its high fat content is one reason why it’s a favorite food of migratory songbirds, who need that energy to fuel their migration. I’ve always admired the resilience of the common spicebush, as it’s one of the few native plants in the northeast that can compete with invasive plants in the forest understory. I grow a male and female here in my garden.

    The spring flowers of common spicebush.

    Eventually I learned that there are some uncommon varieties of the common spicebush. My favorite local nursery Broken Arrow Nursery, which specializes in rare and unusual plants, sells Lindera benzoin ‘Rubra’, a male variety with red flowerbuds. This variety was discovered on the side of the road by Dr. Brian Maynard of the University of Rhode Island. I got to meet him and take cuttings from one of his plants, but I failed to get them rooted or grafted. As it turns out, the common spicebush is very difficult to propagate.

    Another almost-mythical form of the common spicebush is Lindera benzoin ‘Xanthocarpa’, a female form with yellow rather than red fruits. This mutation occurs randomly in wild populations, and is exceptionally difficult to find because it can only be seen when the bushes are fruiting. In the winter of 2021 I searched through all sightings of fruiting Lindera benzoin on iNaturalist and managed to find a few examples of this form. You could say that my searching “bore fruit”. Unfortunately the seeds I received from a kind iNaturalist member failed to germinate.

    I’ve always thought it would be funny to grow ‘Rubra’ and ‘Xanthocarpa’ side by side. You’d have a male spicebush with red flowers that should be yellow next to a female spicebush with yellow fruits that should be red. Sadly I’ve been unable to make it happen, though I continue to try!

    Global distribution of the genus Lindera based on iNaturalist observations.

    As the years have gone on, I’ve learned to appreciate the other non-native members of the genus Lindera as well. There are far more spicebush species in Asia than there are in North America after all. Two of my favorites are Lindera angustifolia and Lindera obtusiloba, the narrow-leaf and blunt-lobed spicebushes respectively. I always seek these plants out on my trips to botanical gardens and arboreta.

    Lindera angustifolia or narrow-leaf spicebush is an East Asian species with excellent fall color and an interesting quirk. Rather than dropping its leaves in the fall, it holds onto them firmly all winter long. I’ve planted a hedge of this species along the back of my property to form a pseudo-evergreen barrier between my yard and my neighbor’s. The wind blowing through the leaves in winter makes a pleasing sound similar to a bamboo grove, without the invasive qualities.

    Lindera obtusiloba or blunt-lobed spicebush is a larger tree-like species that has three-lobed leaves similar to our native Sassafras. The blunt-lobed spicebush’s most striking feature is its reliable fall color. It turns a vibrant yellow-orange every fall without fail, even in woodland settings or when conditions for fall color are poor. The Plants for a Future database says “Young leaves are fried and used as a Buddhist ceremonial dish”, but I’ve found no evidence of this. I guess I’ll have to fry some up sometime and have a taste.

    Both of these Asian spicebushes have yellow flowers in the spring, similar to the common spicebush. The blunt-lobed spicebush has larger flowers in proportion to its larger overall size, while the flowers of the narrow-leaf spicebush are hidden behind its persistent leaves. The Asian spicebushes also produce a small fruit, which is decidedly less edible than the native species. On the one occasion that I ventured to taste it I was immediately punished by its terrible bitterness! As far as spicebush fruits are concerned, you could say that the fruits of the common spicebush are uncommonly delicious.

  • Fiveleaf Aralia – The Incredible Edible Hedge

    Back in the spring of 2022 I was trying to solve a garden problem that had been plaguing me for some time. One edge of my front lawn, where I wanted to grow a food forest, connected seamlessly with my neighbor’s front lawn. The shared border of our properties is roughly 30 feet (9 m) long and highly visible to passersby on the sidewalk and street. If I wanted to grow a garden in this spot, I would need a physical barrier to prevent the neighbors from mowing down or walking on my valuable plants. In addition, I wanted to make sure that mulch I put down in this area didn’t migrate onto my neighbor’s property. A fence would be the obvious solution to this problem, but I thought it would be too mundane a solution for such a highly visible part of the yard. I wanted my yard to inspire others to garden, and this part of the yard would be the first thing people see when coming down the street.

    The problem area

    So I decided that a small ornamental hedge would be the ideal solution. The hedge should be under 4 feet (1.2 m) in height so that I could see over it while backing out of the driveway, and should be under 2 feet (0.6 m) in width so that it wouldn’t take up too much of my limited gardening space. Of course, since I was planning on growing a food forest, I was also looking for a plant that was edible or useful in some way. The hedge in question would have to meet all of these requirements on top of being well-adapted to the conditions of the site: a dry and sunny location in USDA zone 6b.

    Traditional boxwood hedges – pretty but not terribly useful.

    As I began my research, the first plant that came to mind was the Japanese flowering quince, Chaenomeles japonica. This is a short Asian shrub in the rose family with attractive flowers and small edible fruits. It tops out at around 3 feet (1 m) in height – perfect – but tends to have a messy habit and naturally grows twice as wide as tall. This means it would require frequent pruning to keep the hedge looking tidy and its width in check. As I thought about it more, I realized that because this species flowers on the prior year’s wood, routine pruning of the hedge would also result in a reduction in flowers and fruits. In this way maintaining the plant as a hedge runs counter to its main uses – fruiting and flowering, making it a poor fit.

    Japanese flowering quince (Chaenomeles japonica) in bloom at the Arnold Arboretum.

    It was at this point that I had a realization. If I could find a hedging plant that had edible leaves, then I could combine the pruning and harvesting into a single action. Growing the plant as a hedge wouldn’t be a negative, but a great way to keep the leaves within reach! Instead of composting the clippings, I could actually eat them, and additional pruning would only stimulate the plant to produce more tender young leaves for me to harvest. If a plant like this existed, it would have a magical synergy between ornamental and edible qualities.

    A hedge of chaya (Cnidoscolus aconitifolius) growing at ECHO (Educational Concerns for Hunger Organization). Photo from Eric Toensmeier.

    Now it may sound odd to the average Westerner to eat the leaves of a shrub, but I had heard about it being done with a few different species in the tropics, such as chaya (Cnidoscolus aconitifolius) and katuk (Breynia androgyna). Was there a cold-hardy plant that could fill that same role in my New England garden? As I do whenever I have questions of this kind, I consulted the Plants for a Future database. I ran a search for all shrubs with edible leaves that could grow in my conditions and began delving into the data.

    An excerpt from the PFAF page for fiveleaf aralia, Eleutherococcus sieboldianus

    As I was poring over the data, one plant in particular stood out to me: fiveleaf aralia – Eleutherococcus sieboldianus. It had reputable citations for the edibility and good flavor of the leaves, was fully hardy, (down to zone 4!) and was even marked as a species suitable for growing as a hedge. Fiveleaf aralia is a woody member of the ginseng family, which contains a number of other shrubs and perennials with long histories of edible and medicinal use. This gave me some confidence that it was at least safe to consume. Its listed height and width of around 8 feet (2.4 m) however seemed at odds with its recommendation as a hedging plant. All of the photos I found of the plant online were of a large sprawling shrub.

    Fiveleaf aralia growing in a woodland setting at Hortus Arboretum in upstate NY.

    So I tried to find examples of this plant being grown as a hedge. In doing so I came across “Experiments with Hedges”, a 1931 publication by famous landscape architect Frank A. Waugh. In this paper Waugh details his experiments with various plant species as hedges, including fiveleaf aralia under its old Latin name Acanthopanax pentaphyllum. Waugh says of the plant: “This makes an excellent hedge if conscientiously pruned. The example in this experiment stands 3½ – 4 feet high and is 3 feet wide.” Right in the ballpark I was looking for! He even provides a great photo of the hedge itself.

    Waugh, F. A. (Frank Albert), 1869-1943. Acanthopanax (woman standing next to hedge), ca. 1925. Frank A. Waugh Papers (FS 088). Special Collections and University Archives, University of Massachusetts Amherst Libraries

    I also learned through a photo on Dave’s Garden, that this species is grown as a formal hedge in Boston’s famous Public Garden. I visited the hedge on one of my trips to the Arnold Arboretum and was impressed with its small size and dense foliage. Upon measuring it, I found that it was maintained at only 3 feet (1 m) tall and 1 foot (30 cm) wide! The individual plants in the hedge were planted with a dense 1 foot (30 cm) spacing. Surely it must require frequent pruning from the garden staff to be kept so small. Apparently some members of the local Asian community had also noticed the hedge, as I came across this complaint that people were in fact harvesting and eating its leaves!

    A beautiful formal hedge of fiveleaf aralia in the Boston Public Garden.

    Frustrated at the lack of any English language information regarding its edibility, I decided to research the plant using its Japanese name: himeukogi or ヒメウコギ. Through this research I learned that fiveleaf aralia has been grown specifically as an edible hedge in the Japanese city of Yonezawa since feudal times. Its planting had been encouraged by the local lords and generals who saw value in its ability to secure property lines with its thorny branches while also providing important nutrition in case of famine. In fact, one of the most common ways the plant is eaten today hearkens back to its history as a famine prevention food. By boiling the leaves and adding them to rice, you can add crucial vitamins and minerals that a rice-only diet lacks, preventing the worst effects of malnutrition. Due to this long history, the people of Yonezawa continue to grow hedges of this plant (and eat them!) to this day.

    A traditional fiveleaf aralia hedge in Yonezawa, Japan. Bamboo is used to provide additional support.

    In addition to the historic use of fiveleaf aralia in Yonezawa, I discovered that there is actually a budding food industry being built up around the plant. Formed in 1999, the “Ukogi Town Yonezawa Hedge Association” has been growing the plant commercially and promoting its use as an edible hedge. They actually have an entire fiveleaf aralia farm that grows the plant for local farmers markets, grocery stores, and for use as a nutritious food additive. Their website is one of the best sources for fiveleaf aralia information on the web, with detailed information about the history of the plant as well as everything you need to know to grow and prepare it. Much to my surprise, they even produced a line of fiveleaf aralia flavored ice cream!

    After reading all of this, my enthusiasm for the plant had turned into a full-on mania. A vigorous and easily-grown hedge with edible leaves, fully hardy to USDA zone 4? I had read everything I needed to know, and was ready to get some plants in the ground. Clearly the plant was safe to eat and in fact tasted pretty good. The only remaining question I had was “where can I get plants?” Only the variegated form was available in the nursery trade, and I was worried that it wouldn’t be vigorous enough to survive in full sun and make a dense hedge. (I would find out later that the variegated form doesn’t taste good anyway.) I couldn’t find the more vigorous green form of the plant for sale anywhere.

    A variegated fiveleaf aralia growing at the JC Raulston Arboretum.

    In my search for nurseries that sold the plants, I discovered that it was a popular shrub species for shade gardens starting around 100 years ago. It appears in countless gardening books and nursery catalogs from the time under its old name Acanthopanax sieboldianus. As it turns out, large populations of this plant still exist on old estates from that era that have been turned into parks or otherwise forgotten. If left unattended fiveleaf aralia spreads by tip-layering to form large clonal colonies similar to a blackberry. They can take over large swaths of woodland in ideal conditions.

    This patch of fiveleaf aralia at the Bartlett Arboretum in Stamford, CT shows its arching habit and attractive silver-gray bark in winter.

    The more prudent of you will understandably have concerns about this invasive quality. Allow me to put some of those concerns to rest. Because fiveleaf aralia spreads primarily by tip-layering, maintaining it as a trimmed hedge completely removes the main way that it gets around. The plant cannot tip-layer unless the branches are allowed to arch over and touch the ground. Fiveleaf aralia is also dioecious, and all plants in the United States appear to be female clones, so it rarely sets seed.

    Still, the species does seem to be expanding its range throughout the eastern half of the United States. While many local invasions of fiveleaf aralia can be explained as escapes from abandoned garden plantings, there are still others which are clearly caused by bird dispersal of the seeds. The good news is that it’s easy enough to remove flowers and fruit clusters from a trimmed hedge should they occur.

    iNaturalist map showing occurrences of fiveleaf aralia in the eastern United States and Canada.

    Eventually with the help of iNaturalist I located a large colony of fiveleaf aralia in a local park where it seems to have spread from a single ancient planting. The patch was growing in full shade on a steep slope along the side of a bridge, highlighting the incredible adaptability of the species. With well over 100 plants in the patch it would be easy for me to dig some up to transplant into my yard.

    And so on a warm day in mid-March I ventured back to the park, dug up 28 small plants, trimmed them back, and planted them in the aforementioned location. I planted at 1 foot (30 cm) spacing as recommended by the “Ukogi Town Yonezawa Hedge Association” website and hoped for the best. It wasn’t long before the plants began to grow in earnest and by June the first inkling of a hedge was visible.

    As my own planting was getting established, I decided to experiment with the culinary properties of the species using leaves harvested from the patch in the local park. Raw the leaves have a green almost celery-like flavor with a bitter finish, but cooked the bitterness is significantly reduced and the flavor is that of a uniquely aromatic green vegetable. Because the bitterness is caused by water-soluble saponins, the main way to prepare the plant is by boiling the leaves. Just like spinach, the leaves cook down a lot when boiled, so it’s important to harvest a lot of them!

    Only the young, tender leaves are edible – older leaves become too tough. This means that in the spring you can harvest all of the leaves off of the plant but throughout the rest of the year only the young growing shoots may be harvested. Thankfully the young leaves and shoots have a clearly visible color difference which makes them stand out. When harvesting the young leaves in spring you have to be careful of the thorns which occur under each leaf cluster. The young shoots are comparatively easier to harvest as you simply snap them off anywhere the thorns haven’t hardened yet. By keeping the plant as a trimmed hedge you can harvest young shoots as late in the year as September.

    Traditionally the leaves are eaten boiled with rice, as tempura, or as an “aemono” or Japanese chopped salad with walnuts and toasted miso all chopped together. I’ve tried all three of these traditional preparations and I enjoy them so much that I make them regularly throughout the year. The aemono in particular is delightful! This video shows its preparation as well as other traditional preparations of the plant.

    Fiveleaf aralia with rice and fiveleaf aralia tempura – delicious.

    In addition to the traditional Japanese uses for the leaves, I’ve also used them to make a quiche, as a topping on pizza, and as a soup ingredient, all with great results. Because the leaves are fairly mild, they’re suitable for a wide range of uses. After boiling the leaves, the water can be pressed out and the leaves may be frozen for future use.

    Vegan quiche made with fiveleaf aralia from the freezer.

    Regarding the nutrition of the plant, fiveleaf aralia could rightly be called a superfood! The word “adaptogen”, which has been so widely used to describe highly nutritious wild food plants, was originally coined to describe Eleutherococcus senticosus, a close relative of Eleutherococcus sieboldianus. While Eleutherococcus senticosus is much too bitter to be used as a food plant, Eleutherococcus sieboldianus can provide similar benefits in a more palatable package. Research on the nutrition of the species is still ongoing, but all indications point to it being a good source of vitamins A, C, E, calcium, magnesium, iron, zinc and folate in addition to the medicinal and antioxidant qualities of the saponins and polyphenols found in its leaves.

    The author with his young hedge in June of 2023 – sheet mulching in progress at left. Photo by Mike Amato.

    The hedge I planted grew quickly and reached full size in around 2½ years after planting. I keep it trimmed to 4 feet (1.2 m) in height and 2 feet (0.6 m) in width. As Frank A. Waugh said in “Experiments with Hedges”, the plant does require conscientious pruning due to its fast rate of growth. This is less of a problem when you’re eating the leaves, because each pruning session is also a harvest session! This is that magical synergy I was looking for!

    The hedge reaching full-size in June of 2024.

    Looking back, I can only say that “the incredible edible hedge” has been a tremendous success. The hedge looks great and is protecting my young food forest admirably. The dishes I’ve made with fiveleaf aralia have become some of my favorites, and I look forward to making them each spring. The fiveleaf aralia harvest is mainly limited by my patience in picking the leaves and shoots, so I’m currently exploring tools to help automate the process such as devices for stripping leaves from branches and a hedge trimmer with a basket for catching trimmings. I’m hoping that others will learn about the many benefits of this plant, and many more “incredible edible hedges” will be planted soon!

    The dormant hedge in February of 2025.