Andrew’s Blog

Memories of Dr. Duke

 Jim and Peggy at home.

One of the world’s leading authorities in the field of herbal medicine and ethnobotany, Dr. James Duke, passed away on 10th December, 2017. Eulogies and reminiscences of Jim, as everyone knew him, no doubt abound on the Internet, however I would like to share my own memories from my period of seven years living in Maryland USA, and teaching at the Maryland University of Integrative Health (MUIH)  – the campus situated just a couple of miles from Jim’s Green Pharmacy Garden home.

I had met Jim during a lecture tour he made down under some years previously, however on my first day working for MUIH I was taken over to the Green Pharmacy Garden, which I was to learn was a defacto extension of the campus, a living outdoor classroom. As the photos below depict,  the MUIH herbal program could boast not only the best outdoors classroom and guest instructor, but the prettiest faculty as well!

Duke & me                            Duke with Bevin, Claudia, Camille
Meeting with Dr. Duke on day 1.

It wasn’t only the outdoor classes that had me visiting Jim’s home on a regular basis, there were regular social occasions, most of which involved music. In previous lives Jim has been a jazz bass player and a singer/songwriter guitarist with a great repertoire of folk and herbal ditties, along with some traditional bluegrass, in which he was usually accompanied by his son John. Often I would visit him for “happy hour” on Friday afternoons, usually with some other MUIH herbies in tow, as in the photo below (apologies for picture quality). The downstairs gallery was always a big hit, with Peggy’s botanical art on display and for sale, along with a selection of Jim’s books.


Jim loved his chardonnay and I loved to share a bottle with him. He no longer ventured to the far away Amazon as in his younger years, in fact there were few occasions when he was drawn outside his home in recent years. So it was a great pleasure to share in some reminiscences over that period.

Much of the time was spent in the garden itself, often showing students or other visitors around. One of my favourite beds was the anise hyssop (Agastache foeniculum) which was invariably covered in butterflies – quite a sight!.


The garden is a repository for some of the lesser-known and rare medicinal plants, from all around the USA and the globe. Below is a photo of culver’s root (Veronicastrum virginicum) one of the best cholagogue and liver remedies used by physiomedical herbalists of old, but which has lost favour among modern practitioners.


Culver’s root, photo is on an angle

The Green Pharmacy Garden was uniqely designed, with various garden beds arranged according to their therapeutic use. Hence there was a leukemia garden (plenty of Madagascar periwinkle), Alzheimer’s (with snowdrops, small-leaved periwinkle), PMS with Vitex and a depression with St. John’s wort, lemon balm etc. You can see what I mean by an outdoors classroom!

Claudia & hypericum oil

Claudia with some Hypericum oil made in the depression garden.

Other features of the garden were the rampant passionflowers (Passiflora incarnata) and giant butterburs (Petasites spp.)

Passionflower                Petastites

During my tenure at MUIH, the herb program switched from a face-to-face delivery to a predominantly online format, this became a challenge for holding events at the gardens, with students becoming increasingly online – many from outside the region. This concerned Jim, as a hand-on teacher himself he despaired that students would no longer visit and the gardens may become, in a way, redundant. I continued to hold classes or events at the Green Pharmacy Garden whevever the opportunity arrived, so that new generations of students got to meet Jim and see the gardens – even if there weren’t always official classes. Of course the Garden does have an existance outside the MUIH world, and regular functions and courses are conducted there, much of it co-ordinated with assistance from the garden intership programme, under the long term directorship of Helen Metzman.

Other fine memories include the annual new years eve parties featuring various guest musicians – from classical to bluegrass –  and my own going away party that Jim and Peggy kindly hosted for me.

The Duke family and associates have put together an announcment, including reference to a memorial event for 2018. I don’t have a link for that, but here is a news report:

Plant collecting Mount Royal

Recently I and a small group from the Hunter Regional Botanic Gardens Herbarium spent a couple of days observing and collecting plant specimens from the Mount Royal area, situated in the ranges that border the north-western portion of the Hunter Valley, NSW. The range is an extension of the Barriginton Tops region, and includes world heritage rainforest among other botanical attractions.


       View of Mt. Royal from walking track to Pieries Peak.

We didn’t actually make it to Mt. Royal itself, but did find a dazzling array of plant life all around. Pieries Peak track is a spectacular walk, near the top one side of the ridge is clothed in rainforest, the track takes you to the edge of the canopy where tops of flowering trees, vines and mistletoe can be spotted. One of the more spectacular and most highly scented specimen is the native frangipani (Hymenosporum flavum), in the Pittosporaceae family – not related to the true frangipani.


At the main picnic area numerous dwarf herbs could be seen emerging from the peaty soil, including native violets and lobelias. From a herbalists perspective there was quite a bit of centaury (Centaurium erythraea ) growing in the grassy areas. It wasn’t quite in flower, however this is still a good time to harvest the plant and make medicine. Back in the Southern Cross Farm, North Rothbury, the plants are in full flower, however this is a slightly different species, C. tenuifolium – the difference will be explained in the following herbal profile.

Common centaury, lesser centaury.  Centaurium erythraea Rafn.


Centaury is an annual herb, growing to a height of 50cm, starting off as a basal rosette. Thin stems then appear bearing simple opposite leaves with a shiny surface, displaying pink flowers arranged in terminal flat-topped compound cymes. The similar species C. tenuifolium is more common at lower altitude in New South Wales. This species loses the basal rosette leaves at the flowering stage, these basal leaves are retained on C. erythraea. (Harden, 1992)


Centaury is a naturalized weed in Australia, commonly seen in fields and pastures during the summer months.


Secoiridoid glycosides: centapicrin, swertiamarin, sweroside, gentiopicroside, centauroside.

Xanthones, flavonoids, triterpenes (Bisset, 1989; Aberham et al, 2011)

Centrapicrin                                                                       Centapicrin (C25H28O12)


Therapeutic indications are based around centaury’s bitter principles (the secoiridoids), which stimulate appetite, increase secretion of gastric juices and are beneficial in chronic dyspepsia.

Centaury is closely related to gentian (Gentiana lutea and other species) however it is a milder bitter than gentian. In Europe it is included in over 40 proprietary medicines, mainly in digestive and cholagogue blends, and some urological remedies.

In vivo studies indicate it has benefits as an antidiabetic and hepatoprotective agent with potential for treatment of non-alcoholic liver steatosis (Hamza et al., 2015).

According to British medical herbalist William Smith in his famous “Wonders in Weeds”, an infusion of the flowering tops is beneficial for languid digestion, heartburn after food or lack of appetite. He further recommends it for liver, gallbladder and spleen disorders, where he combines it with barberry bark and ginger or cayenne. For a general tonic he combines it with raspberry leaves and cayenne pepper in a tea, sweetened with honey while for gastric ulcers he combines it with astringents, cranesbill, raspberry leaves, agrimony and avens (Smith, 1977). While some authorities such as the German Commission E monographs contraindicate bitters such as centaury for stomach ulcers, physiomedical-style herbalists such as Smith promote the use of bitters and astringents, even cayenne has its adherents for treatment of ulcers.

20171129_095424 Centaury, just harvested for tincture making.

Centaury is commonly taken as an infusion, and can be made into a simple tincture. A medicinal wine preparation recipe can be found here

There are few if any safety issues with this herb, however as with all bitters, low dose is best.


Aberham, A. et al. (2011). Analysis of iridoids, secoiridoids and xanthones in Centaurium erythraeaFrasera caroliniensis and Gentiana lutea using LC–MS and RP-HPLC. J. Pharm & Biomed Analysis 54(3), 517-525.

Bisset, NG. (ed.) (1989). Max Wilchtl Herbal drugs and phytopharmaceuticals. Medpharm, CRC Press.

Hamza, N. et al. (2015). Effect of Centaurium erythraea Rafn, Artemisia herba-alba Asso and Trigonella foenumgraecum L. on liver fat accumulation in C57BL/6J mice with high-fat diet-induced type 2 diabetes. J. Ethnopharmacology, 171, 4-11.

Harden, G. (ed.) (1992). Flora of New South Wales Vol. 3. Royal Botanic Gardens, Sydney.

Smith, W. (1977). Wonders in weeds. CW Daniel, UK.




Plant medicine from the Hunter Valley

There is increasing awareness that Australian plants provide a unique source of materials and ingredients for medicinal purposes, foods, skin care and cosmetics. Indeed I recently reviewed a book that demonstrates how far we have come towards developing successful industries around some of our native food species.

Australian Native Plants Cultivation and Uses in the Health and Food Industries book cover

At a suggested retail cost of over $200 I would be recommending it for libraries across Australia, so that we can all get access to this excellent resource.

One of the edible natives that has always fascinated me is the geebung (Persoonia spp.) Living at North Rothbury I have Australia’s most highly endangered plant species, Persoonia pauciflora growing nearby, and I am cultivating several specimens here on the Southern Cross Farm. Another species, P. linearis, grows prolifically on the farm, the only problem is never finding any ripe fruit, I think the birds always beat me to it!

Today I visited some people over Laguna  way who have Persoonia pinifolia growing on thier property, a species of limited distribution. The tall shrub with attractive bark and a weeping habit has purple, and apparently delicious fruit.

File:Persoonia pinifolia fruit (6087202920).jpg

Persoonia pinifolia, image from Wikimedia Commons

In 1997 the Australian National University investigated the fruit of a hybrid specimen between P. pinifolia and P. linearis, and isolated a previously unknown chemical (a phenolic glycoside ester) with potent antibacterial activity, and anecdotally the plant has been used to clear up skin infections attributed to Staph. aureus (golden staph). Given the issues with MRSA (resistant staph infections) this seems like a lead worth following up on, however to my knowledge there has been no follow up. Anyone who is interesting in testing out topical applications based on P. pinifolia should contact me at

Here endeth my first ever blog, hopefully there will be more to follow, especially if I find that anyone is reading it.

Ref. MacLeod, JK, Rasmussen, HB & Willis, AC. (1997). A new glycoside antimicrobial agent from Persoonia linearis x pinifolia.  Journal of Natural Products 60, 620-622

It’s springtime in Eastern Australia

While all seasons have their good points, for me the month of October is just about perfect in this part of the world. The proviso is that some spring rain has arrived to follow on from the normally dry winter. This year it has been particularly dry, and with really no rain of note since early June it was turning into the worst kind of spring – a brown one. Fortunately the latter part of October brought widespread rains, making for green pastures and blossoming trees, shrubs and vines. The silky oaks and jacarandas are  as vividly colourful as usual, and as I travel north from the Hunter various Melaleucas are displaying their creamy white blossoms in great profusion – the most notable being what is often referred to as “snow-in-summefilemelaleuca_linariifolia_-_leaning_pine_arboretum_-_dsc05487r”, Melaleuca linariifolia.

Springtime in Eastern Australia

It is my birth month and the middle of spring, what is not to like about October in Australia? Well to be honest it didn’t start out so well, over three months without any rain of note was taking its’ toll, and the colour of the landscape was gradually turing brown. However the spring rains finally arrive in the second half of the month, providing green pastures and an abundance of flowering trees, vines and blossoms of all kinds.

Along with the regular October colour spectacle provided by the silky oak and jacaranda trees, most of the Melaleucas are also providing a show of creamy-white blossom, the most outstanding being the “snow in summer” Melaleuca linariifolia, one of only two species used as a source of authentic tea tree oil.


Last week saw me travelling up from the Hunter Valley to Tweed Heads on the Queensland border to speak at the Aromatica Conference, and while the white flowering Kunzea ambigua was a dominant roadside specimen along the M1 motorway during the early stages of the trip, further north the Melaleucas took their place. Having stopped at a friends tea tree plantation to collect some oil and plant specimens of Melaleuca alternifolia, I was able to use my variously gathered specimens to illustrate the topic, “Know your Chemotypes and Australian essential oils”. The fact is that to meet world and Australian standards for tea tree oil, not only does it need to come from one of the two species referred to above, it also needs to be the correct chemotype, ie with a chemical profile with minimal levels of 30% terpinen-4-ol and maximum levels of 1,8-cineole. Other chemotypes of the two species have essential oil profiles with much lower levels of terpinen-4-ol and higher levels of 1,8-cineole. These are still great essential oils, but they can’t be marketed as tea tree oil, so there is naturally much less attention paid to them.

I was able to produce specimens of the authenticated chemotype of M. alternifolia I’d just collected at the tea tree plantation, whereas the M. linariifolia specimen was collected from the wild, and could have only be authenticated in a lab by GC analysis. The point of circulating the two specimens around the room during my talk, was to see whether the two could be distinguished using the human sensory apparatus ie the nose! In my opinion the two specimens were clearly different, hence it is unlikely the M. linariifolia specimen could produce genuine tea tree oil, however I believe that it produced the most pleasing, more floral aroma compared to tee tree oil – often tagged as being a “medicinal” smelling oil.

Along the banks of the Brisbane river where I am currently staying, tea trees are also in bloom, however there are mainly the sweet smelling M. bracteata. This species is popular for planting, however the oil it produces is high in phenolic ethers, some of which may be toxic or even hallucinigenic. To me it has one of the least pleasant odours of the Melaleuca genus.