Welwitschia mirabilis, Seed

Welwitschia mirabilis is a species I never cease to be excited about. This species is endemic to the Namib desert, in Namibia and Angola. It is a monotypic species. Which appears to have remained unchanged for tens, maybe even hundreds, of millions of years. Pretty incredible, but it gets better!

W. mirabilis produces two cotyledons upon germination. These grow into two leaves. These leaves remain as the plants only leaves, for its entire life. Each leaf can reach four metres in length. Considering W. mirabilis can live for over a thousand years, its amazing.

Eli (head gardener) ordered some seeds a while ago and they came yesterday. They were soaked for 24 hours then sown in deep tubes. W. mirabilis resents root disturbance, so it must be repotted before it reaches the base of the tube. 

Ananas comosus, Micropropagation

Yesterday me and Kady (Curatorial scholar) visited the Palestine Polytechnic University. Dr Rami Arafeh gave us a tour of the micropropagation lab. If you are interested in trying micropropagation, here is a link to a protocol. Rami was kind enough to give us a jar of Ananas comosus which he had propagated. Photos below show the growing room and the A. comosus being transplanted.

Tetrastigma voinierianum, Cuttings 

The large lianas are a hugely important part of the Tropical collection. These plants will quickly cover hard surfaces in the glasshouse and soften the edges. A big component of the lianas in the collection are the Hoyas, shown in previous posts.
A number of the other liana species are members of the Vitaceae family. One of those is Tetrastigma voinierianum. Native to Laos and Northern Vietnam this species populates tropical rainforest areas. T. voinierianum has large waxy leaves in a shape much like what’s found in Vitis. This species is fast growing so should soon fill space in the glasshouse. Below are the plants in the nursery.

Cuttings of two nodes in length were taken 8 weeks ago. They have rooted so were potted into 3l pots. Sadly I don’t have photos of the cuttings before striking, below are photos of the rooted cuttings and the potted plants. Leaves should form soon.

These cuttings rooted easily (95% success) with very little attention. No rooting hormone was used and the cuttings were kept under a propagation bench, in the shade. I probably should have added osmocote to the tubes of cuttings at week six, to stimulate shooting. That would have been optimal. 

Agathis robusta, Softwood Cuttings 

Conifers can be difficult to propagate vegetatively. Even if they root freely, it tends to take a while. In the glasshouse there is an old specimen of Agathis robusta, but it’s in poor condition. The trees main stem was cut down to around 40cm, the plant is just a stump with some young shoots.
This plant is unlikely to form a new leader and grow into a strong tree. Because of this it would be good to propagate it. The fresh growth lends itself well to cuttings, so today some were taken. All the cuttings are tips for maximum rooting potential. Cuttings are four nodes long, dipped in rooting hormone, potted nine per 11cm pot. Photos below.

Agathis robusta is a large (50m) evergreen conifer. Agathis is a genus in the Auricariaceae family, British readers will know Araucaria araucana (monkey puzzle tree) as it is a commonly cultivated family member. A. robusta grows in Queensland and has two known populations, its uncommon in cultivation. Hopefully the cuttings take as this is a great species to have. Probably more use in the Tropical Australia section than the glasshouse though. A full sized tree below.

Not my image, link to creator.

Hoya Leaf cuttings 

The final Hoya species left to propagate is H. aff. Mcgregorii. The plant has large, attractive leaves. From reading limited accounts online the plant should also have fragrant flowers. The Garden has one small specimen. 
Hoyas root easily from a single node so leaf cuttings with a small section of stem were taken. The cutting is inserted into an 11cm pot at an angle. The medium level should be just above the leaf base. To find out if the flowers are as described, one stem was left on the plant, this should flower soon. The photos below show H. aff. Mcgregorii and the cuttings. 

Tropical Collection Inventory 

Before planting a full inventory of the the gardens tropical collection is required. This is not work I’m used to doing. Kady the gardens curation scholar helped me out. The part of the process I find hardest is setting up the excel sheet. 

Excel is a brilliant program. It can do so much especially for an inventory like this. I have an iPad which means we can fill the spreadsheet whilst in the glasshouse. Kady produced the spreadsheet on Friday and we begun filling it out yesterday. 

The spreadsheet uses data from Irisbg (the gardens database) and other information Kady found in records. As we go through we mark plants that are listed as existing and exist, as well those that are not yet recorded. Hopefully we will have everything recorded by tomorrow afternoon. A sample of the spreadsheet below.

We have a fair few blanks from plants which have died over the years, still a pretty good collection. The non existent plants must be marked as dead in the database. Some plants lack accessions so will have to be resolved. Others need indentification, thankfully we don’t have many left like this.

This represents a huge step in the project for me. My aim was to provide a collection of strong healthy plants that was accurately recorded before planting. Almost every plant has now be repotted and attended to, recording them marks the concluding stages of the project.

Hoya archboldiana, Cuttings 

More of the Hoya cuttings are rooting, so can be repotted. Hoya parasitica and Hoya archboldiana are the most recent species to root. These cuttings were taken in the same manner as the Hoya cuttings I described in a previous post. The only difference is the cuttings are smaller so multiple cuttings were put into 3l pots. Photos below.

Hoya archboldiana is a great plant. Discovered in Papua New Guinea in 1913 it quickly made it into cultivation. This species has 20cm long, waxy leaves and impressive pink flowers. It oozes tropical vibes. Below I’ve included some photos from Vermont Hoyas, it’s an interesting website about growing plants a long way from their comfort zone. Excellent pictures too.

Callisia fragrans, Cuttings 

Sometimes the common plants are the best. Many gardeners turn their noses up at certain species they “see everywhere”. The upside of seeing something everywhere is it indicates it’s easy to grow. Callisia fragrans is one of those plants.
C. fragrans is a fleshy herbaceous plant in the Commelinaceae family. Though endemic to Mexico it is common in cultivation. C. fragrans has been used as a houseplant in Europe since the early 1900’s. The foliage is very attractive and it grows well in shade. 
Propagation is easy, cut a stem below a node, strip the foliage and insert the stem into a moist medium. I took cuttings three weeks ago and they have already filled their containers. Plants like this will make excellent ground covers in the conservatory. Photos below.

Material: Semi-succulent 
Action: Cuttings 
Treatment: None
Medium: 1:1:1 Coir:Perlite:Vermiculite 

Material: Plants
Action: Transplanting 
Treatment: None
Medium: 8:5:2:2 Coir:Perlite:Tufa:Vermiculite + osmocote

Pavonia cauliflora, Semi-ripe Basal Cuttings 

Today I repotted some cuttings from Pavonia cauliflora. The name of this species is disputed. The JBG has it labelled as Gothea cauliflora, whilst plantlist shows this name as unresolved. The accepted name on plantlist is Pavonia cauliflora, so that is what I will use.
P. cauliflora is pretty rare, it’s range covers only a small part of Brazil. It’s a good shrub too. This species has large evergreen leaves and cup shaped red flowers which emerge from the stems. It grows happily in heavy shade, I’ve now moved it into 3/4 day sun and it’s still thriving. A very versatile plant.
Obviously being so useful P. cauliflora had to be propagated. Our plant is very small and only had a few stems. I managed to take four cuttings a month ago. I potted three of them on today into 11cm pots, one failed to root. The root systems aren’t hugely developed but I want the plants growing with nutrients as soon a possible. Shown below.


Material: Plants

Action: Transplanting 

Treatment: None

Medium: 8:5:2:2 Coir:Perlite:Tufa:Vermiculite + osmocote 

Irrigation: Handwater, once daily
The cuttings I took are described as “basal cuttings”. The cuttings are taken in much the same way as a regular semi-ripe cutting. The key difference is only nodes adjoining stems and shoots are severed. At this point the shoot should have a collar like bulge. Instead of cutting above as you would when pruning, the cut is made lower than the collar. This severs the lower node and provides a large surface area for rooting. To further increase rooting area I wounded the stems, though looking at the point of root formation it seemed to make no difference. Cuttings shown below.


Material: Semi-ripe

Action: Basal Cuttings

Treatment: Rotting hormone 

Medium: 1:1:1 Coir:Perlite:Vermiculite 

Irrigation: Handwater, once daily
The mother plant has produced fresh growth so more cuttings can be taken soon. The cuttings transplanted today should have filled the 11cm pots in four weeks. Hopefully they will be just about filling up 3L pots, come planting time.